For some reason, lamdas passed to a particular overload of Create were not marked static.

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/Append.cs

@@ -31,7 +31,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 (value, scheduler),
-                async (source, state, observer) =>
+                static async (source, state, observer) =>
                 {
                     var d = new CompositeAsyncDisposable();
 
@@ -57,7 +57,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 values,
-                (source, values, observer) => source.SubscribeSafeAsync(AsyncObserver.Append(observer, values)));
+                static (source, values, observer) => source.SubscribeSafeAsync(AsyncObserver.Append(observer, values)));
         }
 
         public static IAsyncObservable<TSource> Append<TSource>(this IAsyncObservable<TSource> source, IAsyncScheduler scheduler, params TSource[] values)
@@ -72,7 +72,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 (scheduler, values),
-                async (source, state, observer) =>
+                static async (source, state, observer) =>
                 {
                     var d = new CompositeAsyncDisposable();
 
@@ -98,7 +98,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 values,
-                (source, values, observer) => source.SubscribeSafeAsync(AsyncObserver.Append(observer, values)));
+                static (source, values, observer) => source.SubscribeSafeAsync(AsyncObserver.Append(observer, values)));
         }
 
         public static IAsyncObservable<TSource> Append<TSource>(this IAsyncObservable<TSource> source, IAsyncScheduler scheduler, IEnumerable<TSource> values)
@@ -113,7 +113,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 (scheduler, values),
-                async (source, state, observer) =>
+                static async (source, state, observer) =>
                 {
                     var d = new CompositeAsyncDisposable();
 

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/Catch.cs

@@ -23,7 +23,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 handler,
-                async (source, handler, observer) =>
+                static async (source, handler, observer) =>
                 {
                     var (sink, inner) = AsyncObserver.Catch(observer, handler);
 
@@ -44,7 +44,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 handler,
-                async (source, handler, observer) =>
+                static async (source, handler, observer) =>
                 {
                     var (sink, inner) = AsyncObserver.Catch(observer, handler);
 
@@ -64,7 +64,7 @@ namespace System.Reactive.Linq
             return Create(
                 first,
                 second,
-                async (first, second, observer) =>
+                static async (first, second, observer) =>
                 {
                     var (sink, inner) = AsyncObserver.Catch(observer, second);
 

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/Concat.cs

@@ -22,7 +22,7 @@ namespace System.Reactive.Linq
             return Create(
                 first,
                 second,
-                async (first, second, observer) =>
+                static async (first, second, observer) =>
                 {
                     var (sink, inner) = AsyncObserver.Concat(observer, second);
 

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/DefaultIfEmpty.cs

@@ -22,7 +22,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 defaultValue,
-                (source, defaultValue, observer) => source.SubscribeSafeAsync(AsyncObserver.DefaultIfEmpty(observer, defaultValue)));
+                static (source, defaultValue, observer) => source.SubscribeSafeAsync(AsyncObserver.DefaultIfEmpty(observer, defaultValue)));
         }
     }
 

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/Delay.cs

@@ -22,7 +22,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 dueTime,
-                async (source, dueTime, observer) =>
+                static async (source, dueTime, observer) =>
                 {
                     var (sink, drain) = await AsyncObserver.Delay(observer, dueTime).ConfigureAwait(false);
 
@@ -42,7 +42,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 (dueTime, scheduler),
-                async (source, state, observer) =>
+                static async (source, state, observer) =>
                 {
                     var (sink, drain) = await AsyncObserver.Delay(observer, state.dueTime, state.scheduler).ConfigureAwait(false);
 

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/DelaySubscription.cs

@@ -27,7 +27,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 (dueTime, scheduler),
-                async (source, state, observer) =>
+                static async (source, state, observer) =>
                 {
                     var d = new CompositeAsyncDisposable();
 
@@ -61,7 +61,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 (dueTime, scheduler),
-                async (source, state, observer) =>
+                static async (source, state, observer) =>
                 {
                     var d = new CompositeAsyncDisposable();
 

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/Distinct.cs

@@ -26,7 +26,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 comparer,
-                (source, comparer, observer) => source.SubscribeSafeAsync(AsyncObserver.Distinct(observer, comparer)));
+                static (source, comparer, observer) => source.SubscribeSafeAsync(AsyncObserver.Distinct(observer, comparer)));
         }
     }
 

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/DistinctUntilChanged.cs

@@ -27,7 +27,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 comparer,
-                (source, comparer, observer) => source.SubscribeSafeAsync(AsyncObserver.DistinctUntilChanged(observer, comparer)));
+                static (source, comparer, observer) => source.SubscribeSafeAsync(AsyncObserver.DistinctUntilChanged(observer, comparer)));
         }
 
         public static IAsyncObservable<TSource> DistinctUntilChanged<TSource, TKey>(IAsyncObservable<TSource> source, Func<TSource, TKey> keySelector)
@@ -40,7 +40,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 keySelector,
-                (source, keySelector, observer) => source.SubscribeSafeAsync(AsyncObserver.DistinctUntilChanged(observer, keySelector)));
+                static (source, keySelector, observer) => source.SubscribeSafeAsync(AsyncObserver.DistinctUntilChanged(observer, keySelector)));
         }
 
         public static IAsyncObservable<TSource> DistinctUntilChanged<TSource, TKey>(IAsyncObservable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector)
@@ -53,7 +53,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 keySelector,
-                (source, keySelector, observer) => source.SubscribeSafeAsync(AsyncObserver.DistinctUntilChanged(observer, keySelector)));
+                static (source, keySelector, observer) => source.SubscribeSafeAsync(AsyncObserver.DistinctUntilChanged(observer, keySelector)));
         }
 
         public static IAsyncObservable<TSource> DistinctUntilChanged<TSource, TKey>(IAsyncObservable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer)
@@ -68,7 +68,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 (keySelector, comparer),
-                (source, state, observer) => source.SubscribeSafeAsync(AsyncObserver.DistinctUntilChanged(observer, state.keySelector, state.comparer)));
+                static (source, state, observer) => source.SubscribeSafeAsync(AsyncObserver.DistinctUntilChanged(observer, state.keySelector, state.comparer)));
         }
 
         public static IAsyncObservable<TSource> DistinctUntilChanged<TSource, TKey>(IAsyncObservable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, IEqualityComparer<TKey> comparer)
@@ -83,7 +83,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 (keySelector, comparer),
-                (source, state, observer) => source.SubscribeSafeAsync(AsyncObserver.DistinctUntilChanged(observer, state.keySelector, state.comparer)));
+                static (source, state, observer) => source.SubscribeSafeAsync(AsyncObserver.DistinctUntilChanged(observer, state.keySelector, state.comparer)));
         }
     }
 

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/Do.cs

@@ -18,7 +18,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 observer,
-                (source, observer, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, observer)));
+                static (source, observer, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, observer)));
         }
 
         public static IAsyncObservable<TSource> Do<TSource>(this IAsyncObservable<TSource> source, Action<TSource> onNext)
@@ -31,7 +31,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 onNext,
-                (source, onNext, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, onNext)));
+                static (source, onNext, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, onNext)));
         }
 
         public static IAsyncObservable<TSource> Do<TSource>(this IAsyncObservable<TSource> source, Action<Exception> onError)
@@ -44,7 +44,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 onError,
-                (source, onError, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, onError)));
+                static (source, onError, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, onError)));
         }
 
         public static IAsyncObservable<TSource> Do<TSource>(this IAsyncObservable<TSource> source, Action onCompleted)
@@ -57,7 +57,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 onCompleted,
-                (source, onCompleted, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, onCompleted)));
+                static (source, onCompleted, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, onCompleted)));
         }
 
         public static IAsyncObservable<TSource> Do<TSource>(this IAsyncObservable<TSource> source, Action<TSource> onNext, Action<Exception> onError, Action onCompleted)
@@ -74,7 +74,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 (onNext, onError, onCompleted),
-                (source, state, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, state.onNext, state.onError, state.onCompleted)));
+                static (source, state, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, state.onNext, state.onError, state.onCompleted)));
         }
 
         public static IAsyncObservable<TSource> Do<TSource>(this IAsyncObservable<TSource> source, IAsyncObserver<TSource> observer)
@@ -87,7 +87,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 observer,
-                (source, observer, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, observer)));
+                static (source, observer, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, observer)));
         }
 
         public static IAsyncObservable<TSource> Do<TSource>(this IAsyncObservable<TSource> source, Func<TSource, ValueTask> onNext)
@@ -100,7 +100,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 onNext,
-                (source, onNext, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, onNext)));
+                static (source, onNext, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, onNext)));
         }
 
         public static IAsyncObservable<TSource> Do<TSource>(this IAsyncObservable<TSource> source, Func<Exception, ValueTask> onError)
@@ -113,7 +113,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 onError,
-                (source, onError, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, onError)));
+                static (source, onError, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, onError)));
         }
 
         public static IAsyncObservable<TSource> Do<TSource>(this IAsyncObservable<TSource> source, Func<ValueTask> onCompleted)
@@ -126,7 +126,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 onCompleted,
-                (source, onCompleted, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, onCompleted)));
+                static (source, onCompleted, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, onCompleted)));
         }
 
         public static IAsyncObservable<TSource> Do<TSource>(this IAsyncObservable<TSource> source, Func<TSource, ValueTask> onNext, Func<Exception, ValueTask> onError, Func<ValueTask> onCompleted)
@@ -143,7 +143,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 (onNext, onError, onCompleted),
-                (source, state, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, state.onNext, state.onError, state.onCompleted)));
+                static (source, state, target) => source.SubscribeSafeAsync(AsyncObserver.Do(target, state.onNext, state.onError, state.onCompleted)));
         }
     }
 

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/DoWhile.cs

@@ -21,7 +21,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 condition,
-                async (source, condition, observer) =>
+                static async (source, condition, observer) =>
                 {
                     var subscription = new SerialAsyncDisposable();
 
@@ -82,7 +82,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 condition,
-                async (source, condition, observer) =>
+                static async (source, condition, observer) =>
                 {
                     var subscription = new SerialAsyncDisposable();
 

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/ElementAt.cs

@@ -18,7 +18,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 index,
-                (source, index, observer) => source.SubscribeSafeAsync(AsyncObserver.ElementAt(observer, index)));
+                static (source, index, observer) => source.SubscribeSafeAsync(AsyncObserver.ElementAt(observer, index)));
         }
     }
 

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/ElementAtOrDefault.cs

@@ -16,7 +16,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 index,
-                (source, index, observer) => source.SubscribeSafeAsync(AsyncObserver.ElementAtOrDefault(observer, index)));
+                static (source, index, observer) => source.SubscribeSafeAsync(AsyncObserver.ElementAtOrDefault(observer, index)));
         }
     }
 

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/Finally.cs

@@ -19,7 +19,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 finallyAction,
-                async (source, finallyAction, observer) =>
+                static async (source, finallyAction, observer) =>
                 {
                     var subscription = await source.SubscribeSafeAsync(observer).ConfigureAwait(false);
 
@@ -47,7 +47,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 finallyAction,
-                async (source, finallyAction, observer) =>
+                static async (source, finallyAction, observer) =>
                 {
                     var subscription = await source.SubscribeSafeAsync(observer).ConfigureAwait(false);
 

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/First.cs

@@ -30,7 +30,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 predicate,
-                (source, predicate, observer) => source.SubscribeSafeAsync(AsyncObserver.First(observer, predicate)));
+                static (source, predicate, observer) => source.SubscribeSafeAsync(AsyncObserver.First(observer, predicate)));
         }
 
         public static IAsyncObservable<TSource> First<TSource>(this IAsyncObservable<TSource> source, Func<TSource, ValueTask<bool>> predicate)
@@ -43,7 +43,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 predicate,
-                (source, predicate, observer) => source.SubscribeSafeAsync(AsyncObserver.First(observer, predicate)));
+                static (source, predicate, observer) => source.SubscribeSafeAsync(AsyncObserver.First(observer, predicate)));
         }
     }
 

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/FirstOrDefault.cs

@@ -30,7 +30,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 predicate,
-                (source, predicate, observer) => source.SubscribeSafeAsync(AsyncObserver.FirstOrDefault(observer, predicate)));
+                static (source, predicate, observer) => source.SubscribeSafeAsync(AsyncObserver.FirstOrDefault(observer, predicate)));
         }
 
         public static IAsyncObservable<TSource> FirstOrDefault<TSource>(this IAsyncObservable<TSource> source, Func<TSource, ValueTask<bool>> predicate)
@@ -43,7 +43,7 @@ namespace System.Reactive.Linq
             return Create(
                 source,
                 predicate,
-                (source, predicate, observer) => source.SubscribeSafeAsync(AsyncObserver.FirstOrDefault(observer, predicate)));
+                static (source, predicate, observer) => source.SubscribeSafeAsync(AsyncObserver.FirstOrDefault(observer, predicate)));
         }
     }