After some more testing, I think this is indeed the case. The problem is that the device has two input channels ("line-in", " external mic"). In alsamixer i can select both as "PCM capture source" (from here) However, the input tab of pavucontrol, i can only select "line in". I switched through all available profiles for the card. But the dropdown only always show "line-in"

Any ideas?

It's Xubuntu 22.04 so most likely PulseAudio.

Unless you're using Arch or Gentoo or similar distros that come with nothing by default, it's pretty much going to have PA or PW.

I don't understand how people always end up messing with ALSA when we haven't used ALSA directly by default on any mainstream distro for nearly a decade. Especially with PipeWire around, ALSA should essentially treated like a low level API you don't mess with unless you have a kiosk application that's gonna take exclusive direct use of ALSA. Even ALSA plugins like dmix/dsnoop are wildly outdated and buggy with modern applications, if they even still support using ALSA directly. Messing with ALSA is a recipe for pain especially if you're not intimate with it. There's very, very few reasons to do anything with ALSA these days.

The correct solution is to just select the correct profile from the sound menu, or change it from pavucontrol. That's it, it's that simple.