Audio devices re-registered by sound widget after every log in

the same issue have been solved here: https://forum.endeavouros.com/t/pipewire-1-0-3-77-1-duplicates-plasma-pa-entries-on-disconnect-reconnect-and-breaks-sound-control/44228
Basically it is bug with pipewire version 0.3.77. you just need to downgrade pipewire and all connected packages back to 0.3.76 or earlier.