Just to confirm your issue with the sound :).
It may be related to pipewire, that should be configured for video-only streams. I believe it must be configured automatically in case you you do not install pipewire-pulse (not included into the repo), but something went wrong (as usual 
).
So, try to reconfigure it by yourself (link):
systemctl --user disable wireplumber.service
systemctl --user enable wireplumber@video-only.service
systemctl --user status wireplumber@video-only.service