Per-application audio capture in OBS is currently in beta and only available on Windows. However, you can get an OBS plugin that allows you to individually capture an application's audio on Linux. This is useful for adjusting the volume of each application, separating applications into separate tracks, or just isolating the audio you want to capture so only the application you want is captured.

https://github.com/dimtpap/obs-pipewire-audio-capture/releases

$ apt install wireplumber

$ systemctl --user --now enable wireplumber

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