So with using #Pipewire it is better to just learn the new tooling for loopbacks. As running:

pactl load-module module-loopback latency_msec=1

“works” but creates audio feedback and kills audio output after a little while.

Yet if I use the new “proper” tooling of:

pw-loopback -m '[[FL FR]]' --capture-props='[media.class=Audio/Sink node.name=my-sink]'

My loopback sink works better than it ever has before

Need to to not be so uncharacteristically stubborn and not fight things.