Fix inverted staleness guard on the /sync reconnect catch-up

Assets/Plugins/StreamChat/Changelog.txt

@@ -19,6 +19,7 @@ Features:
 
 Fixes:
 
+* Fix the 30-day staleness guard on the reconnect /sync catch-up computing its age backwards (lastEventReceivedAt - now, which is negative for any past timestamp), so the guard never fired and /sync was called even with a LastSyncAt the server rejects. Also removes a dead local that was almost certainly the intended operand.
 * TaskUtils.LogIfFailed now logs connectivity/transport failures as warnings instead of errors/exceptions. The SDK fire-and-forgets its connect, reconnect, and state-restore operations through LogIfFailed; when the device is offline these fail with HttpRequestException / WebException / SocketException / IOException / TimeoutException, which the reconnect flow recovers from - so surfacing them at error severity flooded crash/error reporting (Sentry, Bugsnag, etc.) with handled, non-actionable noise. Genuine (non-connectivity) failures still log as exceptions. Complements the connection-attempt-timeout fix from PR #213.
 
 v5.5.0:

Assets/Plugins/StreamChat/Core/LowLevelClient/StreamChatLowLevelClient.cs

@@ -445,10 +445,10 @@ public async Task FetchAndProcessEventsSinceLastReceivedEvent(IEnumerable<string
 
             var lastEventReceivedAt = _disconnectionLastEventReceivedAt.Value;
 
-            var currentServerTime = DateTimeOffset.UtcNow.ToOffset(lastEventReceivedAt.Offset);
-
-            // Check if less than 30 days
-            var diff = lastEventReceivedAt - _timeService.Now;
+            // Check if less than 30 days. Past that the server rejects LastSyncAt, so this only
+            // skips a request that was certain to fail — it is not a recovery path. The SDK has no
+            // re-hydrate fallback of its own, so bridging a gap this large is the consumer's job.
+            TimeSpan diff = _timeService.Now - lastEventReceivedAt;
             if (diff.TotalDays > 30)
             {
                 return;