I suspect this might be a Firefox bug except that all was working fine and seemed to all of a sudden break. This did not start happening immediately after any update or system change.
Obvious and easily repeatable symptoms are playing a youtube video on Firefox. Audio will be turned off. If you go into settings and move the firefox audio slider to full it will only stay there for a brief period. If you pause the video, skip forward or start viewing a new video the audio setting will revert back to zero. Incredibly annoying.
No other apps seem to exhibit this problem. I did go "under the hood" as recommended in relevant answers posted here and changed the media settings as recommended. This did not help.
Seems to only effect youtube video playbacks based on superficial testing. Rumble videos work as expected.
Wondering if I have to just wait for a FF update or if there is a way to patch in a fix.
Turns out, this was due to a bug caused by youtube. Youtube apparently fixed it after around 24 hours.