Since Gnome 44 there is a new UI to show apps (i.e. messengers, sync clients, …) that run in the background. It is supposed to take the place of the tray icons. In my experience it’s basically not working, though.
The only app I use that uses the UI is the nextcloud client. But that thing’s autostart seems to be very unreliable and most of the time I have to start it manually after booting. Could be an issue with the app and not with Gnome, but I don’t know.
I also use Telegram and Element, but both still seem to use the old tray icons that you now need to install an extension for to work. Meaning that with vanilla Gnome when you close the Telegram window, the app is stopped and can’t receive massages in the background.
Is the new UI broken or are app developers just not implementing it into their apps or what’s wrong with the current situaltion?
I could be completely wrong, but the fact, that you stated, that Telegram doesn’t receive messages without the tray icon leads me to believe that they are doing background services wrong. Because the status icon in the tray is supposed to be exactly that. The service itself shouldn’t be tied to that.