

It was this for me, but it only works in one direction - when turning it down. So turning down YT volume means turning down system audio, then turning up YT audio is just turning up the YT audio. Insane behaviour. There is a way to turn this off in Firefox flags (about:config). This shit also messes with your system mic volume on MS Teams.












Closest I can find is:
media.peerconnection.enabled
This disables all the WebRTC cancer.
In chrome you can also search for WebRTC but that’s the culprit I think.
In addition I’d recommend giving this a read:
https://bugzilla.mozilla.org/show_bug.cgi?id=1422637
Especially comment 136
Look at the mentioned media scale flag too.
And this other thread:
https://bugzilla.mozilla.org/show_bug.cgi?id=1515549
Good fucking luck.
Mozilla can’t put together a half way functional browser to save their life and lick up every enshittification doohickey that falls of the back of the burning Trainwreck that is Google.