Comment 53 for bug 2004532

"snap refresh --channel candidate/core22 firefox" worked for me.
and I have enabled VAAPI on this firefox successfully.

attached log
$ LIBVA_DRIVER_NAME=radeonsi MOZ_DISABLE_RDD_SANDBOX=1 MOZ_WEBRENDER=1 MOZ_ENABLE_WAYLAND=1 MOZ_LOG="PlatformDecoderModule:5" firefox >& firefox.log

[reference]
https://ubuntuhandbook.org/index.php/2021/08/enable-hardware-video-acceleration-va-api-for-firefox-in-ubuntu-20-04-18-04-higher/
https://www.linux-magazine.com/Issues/2021/243/Firefox-VA-API-Integration