Missing push notifications

[stefanceriu]

Original report

I tried around with notifications a bit because I was missing some of them. What I noticed is this: Assume you have the app open and have a room open with alice. You talk but at some point you lock your phone, with the room still open in the background. Now when Alice sends you two messages, one with: "hello" and one with "how are you", I can observe a notification for "hello" but as soon as the "how are you" message comes through, the notification with "hello" gets removed and I am only left with the "how are you" notification.

https://github.com/vector-im/element-x-ios-rageshakes/issues/856

[stefanceriu]

After talking with @pixlwave about this what believe happens is that the app keeps running in the background (because of the 30sec sync task) and it keeps marking newly received messages as read, as if the user actually saw them.

We should observe the application state and stop sending read receipts for new messages while the app is not in the foreground

[manuroe]

Dup of #1923. Notifications that disappeared is part of the symptom we observed when fixing the issue.