Merge pull request #38027 from dukenv0307/fix/37612

fix:  re-join thread after leaving thread and returning with back button

src/pages/home/ReportScreen.tsx

@@ -123,7 +123,7 @@ function ReportScreen({
     const {translate} = useLocalize();
     const {isSmallScreenWidth} = useWindowDimensions();
     const isFocused = useIsFocused();
-
+    const prevIsFocused = usePrevious(isFocused);
     const firstRenderRef = useRef(true);
     const flatListRef = useRef<FlatList>(null);
     const reactionListRef = useRef<ReactionListRef>(null);
@@ -362,6 +362,17 @@ function ReportScreen({
         // eslint-disable-next-line react-hooks/exhaustive-deps
     }, []);
 
+    // If a user has chosen to leave a thread, and then returns to it (e.g. with the back button), we need to call `openReport` again in order to allow the user to rejoin and to receive real-time updates
+    useEffect(() => {
+        if (!isFocused || prevIsFocused || !ReportUtils.isChatThread(report) || report.notificationPreference !== CONST.REPORT.NOTIFICATION_PREFERENCE.HIDDEN) {
+            return;
+        }
+        Report.openReport(report.reportID);
+
+        // We don't want to run this useEffect every time `report` is changed
+        // eslint-disable-next-line react-hooks/exhaustive-deps
+    }, [prevIsFocused, report.notificationPreference, isFocused]);
+
     useEffect(() => {
         // We don't want this effect to run on the first render.
         if (firstRenderRef.current) {