One thing that I haven't been able to get over from my switch from Chrome is the way muting tabs works. While the interface is cleaner than Chrome's, where you can mute individual tabs and not just entire sites unless you use an extension, the actual muting of the tab is surface level. What I mean by surface level is that the firefox tab mute will mute the audio, while the Chrome mute will discontinue the audio path completely allowing a device that uses multipoint to switch audio channels.
I don't know the details of how or why this happens, but I would love a solution to this that doesn't involve me closing the tab to switch audio than opening the tab again.