Interesting. I've been using the Fairphone 4 with /e/OS in the US on Mint for about two months, and I have encountered none of those issues.
The issue that's bugged me is occasionally when I'm using Bluetooth audio, the volume "locks". For whatever reason it decides whatever the current volume is, that's the max or min, and I can only adjust in one direction from there.
Yes, that one is weird... Using the device to set volume usually helps get it "unstuck" in my case, but to be honest, I didn't investigate more than that. Annoying, but easily fixable (for me).
The issue that's bugged me is occasionally when I'm using Bluetooth audio, the volume "locks". For whatever reason it decides whatever the current volume is, that's the max or min, and I can only adjust in one direction from there.