"reverse" loopback on pipewire using a single interface

Hello everyone,

I’m almost certain this problem is quite easily fixable, but I haven’t yet found any solution:

While trying out my new Focusrite Scarlett Solo Gen4 with an AT2020 and HD6xx, I’ve (or rather my friends in Voice Chat have) noticed some applications being “looped” into the input. Contrarily to your classical, and often wanted input-to-ouput loopback, I am currently getting e.g. CS2, Firefox, youtube-music-bin outputting on the wanted output of the interface, as well as outputting into the input of the interface, thus sending my game’s audio into Voice Chat. The reverse loopback is linked to the (software) output, but not to the hardware volume output (i.e. the open-backed headphones are not the issue).

The issue persists even when no microphone is plugged in, I’ve confirmed this using pavucontrol, where (with hardware volume turned off) the output levels matched the input levels. I should stress again that this is only an issue with the output and input being on the same interface/sound card. Using another amp, the problem obviously isn’t noticable anymore.

I couldn’t reproduce the same behaviour on Windows or using my motherboard’s audio on Linux. On another machine running Manjaro KDE with Kernel 6.4.16, I observed similar behaviour.

Thanks for the help, looking forward to any ideas you might have

I could also reproduce this behaviour on kernels 6.6.0rc4-1, 6.5.52-r8-1 and 5.15.133-1; as well as on my steam deck on via its dock on stock configuration. The issue persits on pulse as well as pipewire

it’s possible that there is a reddit thread on r/Archlinux (links arent allowed) about a similar issue, however they didn’t find a solution. For anyone finding this thread in the future, one recommended solution was to check alsamixer for any loopback settings that may have been enabled