I just updated firefox to v98 and noticed that youtube videos stop playing. When I start firefox from a terminal I get the same error repeatedly:
libva info: VA-API version 1.13.0 libva info: Trying to open /usr/lib/dri/radeonsi_drv_video.so libva info: Found init function __vaDriverInit_1_13 ATTENTION: default value of option mesa_glthread overridden by environment.
apart from media playback firefox seems to run fine but I had one hard system freeze.
I also don’t have any custom environmental variables for mesa set, as far as I can tell.