New comment by Duncaen on void-packages repository

https://github.com/void-linux/void-packages/issues/34596#issuecomment-1189559492

Comment:
https://bugzilla.mozilla.org/show_bug.cgi?id=1345661

Audio in firefox is a little more complicated than just the cubeb backend due to sandboxing and having separate content processes. Mozilla disabled alsa support a long time ago and basically said that they don't support it any further, there are still people who afterwards contributed patches to make it work and they landed upstream. But I fully understand why they don't support it, the alsa user experience and the api in general is simply not user friendly and doesn't work out of the box for most users.

I would suggest you to use a sound server, like pulse or pipewire, if you still want to use alsa for some reason, look up how to debug libcubeb and how to debug sandbox issues in firefox, both have their own environment variables for more verbose logging.