Comment # 6 on bug 1197630 from Takashi Iwai

... or we can check the behavior or PulseAudio at first.  Unless you install
wireplumber-audio package and pipewire-pulseaudio package, PA should manage the
sound device instead of PW.

If so, at first, please use pavucontrol instead of GNOME mixer.  Make sure that
the another device is set for the default device in Output tab of pavucontrol.

If setting the default doesn't help, try to comment out the line in
/etc/pulse/default.pa with:
  load-module module-switch-on-port-available
for disabling this module.