> One is the audio sometimes randomly jitters while simply playing music

I encounter the same issue from time to time. Almost consistently reproducible when I update the kernel and the VirtualBox driver needs to be recompiled (and there's no cap for that process that it should use max X% of CPU).

As pipewire is within the user session I would assume higher system load would induce some latency and cause the jitterness.

But in the end I'm just making assumptions, and correlating.