You are right. I’ve corrected my comment

There’s also qobuz for your more mainstream music needs. And you can always use a YouTube downloaded like yt-dlp together with a music tagging tool like MusicBrainz Picard.

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.

Is the new UI broken or are app developers just not implementing it into their apps or what’s wrong with the current situaltion?

Both, kinda. The new UI relies afaik on xdg-portals to get which apps are running in the background. Therefore only flatpaks should show up; but they should show up automatically, without any tweaks by the devs.

Also the UI only displays that an app is running in the background. It can’t communicate any type of status information.

The Linux support of Snapdragon SOCs for desktops and laptops is unfortunately severely lacking. Qualcomm pledged to provide upstream divers, but then the Windows drivers turned out to be a mess and the Linux version had to wait. It is nowhere near production ready. Most of the hardware enablement work is currently as far as I can tell being done by German OEM Tuxedo Computers because they are working on a Snapdragon powered laptop that ships with Linux. But even their work was impacted by Qualcomm stalling (the linked blog article lists Christmas 2024 as their target release date and that didn’t happen).