Update IntlProvider.tsx

frontend/src/locale/IntlProvider.tsx

@@ -49,6 +49,7 @@ const getFlagCodeForLocale = (locale?: string) => {
 	const specialCases: Record<string, string> = {
 		ja: "jp", // Japan
 		zh: "cn", // China
+		vi: "vn", // Vietnam
 		ko: "kr", // Korea
 	};