In Ubuntu 20.04 LTS if you had two (or more) Firefox tabs which were both playing some audio or video then the Gnome dock(?) UI (the pop-over from clicking on the middle of the top bar, where the date shows) would offer two (or more) separate entries to control those audio sources. The pause key on my keyboard would control whichever source was playing first (and it seemed to remember which one that was even when the first one was paused and another tab played something).
This was useful when e.g: using YouTube Music for background music, but then wanting to pause it to watch a video in another tab. I could easily use the pause key to pause the background music, watch whatever video and then use the pause key to continue the background music.
Since upgrading to 22.04 it seems that Firefox as a whole only gets a single entry in that menu, rather than getting a separate entry for each tab.
This has a number of consequences:
- if I allow the video to start playing before pausing the background music, I can no longer use the pause key to pause the background music (instead I need to find the tab, which I keep in a different window, in a different workspace) and pause it manually
- I can't use the pause key or even the menu to continue playing the music when I'm done with the video as it has been replaced in the UI by the newer video
The behaviour when I have two separate programs which both play something has similarly changed -- the most recently played is controlled by the pause key (rather than the oldest, which I think is what used to happen), however I do at least get two separate entries in this case.
This feels like a bug to me, however I'm not sure what the various components are which are involved (e.g: what's controlling this -- is this Firefox or something in Gnome? what's the dock UI called?). Is there a setting to flip this back?
I'm aware that in 22.04 Firefox is now a snap rather than a native debian package. Could that be related? (It looks like there's a way to switch back to a debian package via How to install Firefox as a traditional deb package (without snap) in Ubuntu 22.04 or later versions?, so I'll give that a go and report back) Edit: the debian packaged firefox behaves the same.
For clarity, here's the menu I'm talking about: 
