When I got my PinePhone Pro (less than two weeks ago) the call quality was good.
Now, after running “pacman -Syu”, it’s horrible. The other person hears loud noise through whole call, and my voice is distorted and metallic. It is practically impossible to understand it.
Not sure, but the initial factory image used to have the pulseaudio and now there is a move towards pipewire and things are not quite there yet with the modem part either. Maybe you want to flash with another image from daily builds …
Please check with any Phosh image first, as it uses the audio stack longer. Plasma Mobile is a hit and miss on Pinephone Pro. You may have better audio on the original Pinephone. The Pro will change a lot.