Comment # 7 on bug 1206760 from Takashi Iwai

Well, are you using PulseAudio for the audio, or are you playing directly via
ALSA API?  In the former case, check whether wireplumber and pipewire-pulse
services are running in user mode,
  % systemctl --user status wireplumber
  % systemctl --user status pipewire-pulse

OTOH, in the latter case (the raw ALSA usage), neither PulseAudio nor pipewire
should have been started.  If such a process is running, it may block your
audio device usage.

And, you can check which process uses the devices via fuser command
  % fuser -v /dev/snd/*