With the iOS/macOS PWA or native app, when its backgrounded, Apple kills all of the websocket connections and then when opening the app again the relay connections were becoming stale and not fetching any new messages since last viewing a channel. But, I think I've solved that now in latest update. Once app comes back into view, it reconnects to relays retries the REQs and loads new messages in a few seconds. So far, has been working relatively well!