Suddenly some apps (I think those that use Alsa directly?) became very quiet, such as Skype. I think it happened after pairing via Bluetooth with an iPhone (to use the PC headphones/mic there). But it’s unpaired now.
Using latest Pipewire, Wireplumber.
As suggested in the Arch wiki I checked volume in
alsamixer → F6, but if I increase from 37 to 100 Skype becomes better but other apps/sounds become too loud, the volume in KDE becomes 100%.
Skype volume in KDE and
pavucontrol is 100%.