Manjaro KDE - After the last update replaces pulseaudio with pipewire, no more audio volume controls

Sorry I am not an expert but I found this
https://bbs.archlinux.org/viewtopic.php?id=264463

so you should google for these errors.

I would remove these configuration files they talk about and reinstall pipewire-media-session

Also check if you have all services installed: reference

Also there are some files in
/home/user/.config/pipewire/media-session.d/

check if you have something with Off in those files.
Follow this:
https://wiki.archlinux.org/index.php/PipeWire