Comment 1 for bug 1902362

I can confirm these issues using the pulse device.
It is an ALSA device that is routed back to pulse and again to ALSA to the final destination.
A long stack with limited feedback to Mixxx.

For low latency it is recommended to use the ALSA devices directly anyway. I am in doubt that this is obvious for all users. :-/

There is also an experimental branch that allows Mixxx to directly connect to PulseAudio.
https://github.com/PortAudio/portaudio/pull/336

I am waiting for a merge to upstream PortAudio for long. I would be happy if you can test it and share your experiences.