Second Update: I changed out the serpentine belt. Immediately all of the electronics in the car seem to operate better (the dash or headlights don't dim when I turn on the radio, etc). But both power door locks immediately started acting just as before, where the switch doesn't always work on the first press. When it does lock/unlock it's noticibly louder/more forceful, but both switches are now finicky instead of just the passenger.
Did you already load test your battery & alternator?
Both were tested at the same time as replacement and battery was brand new at beginning of year.
Check the switch. You may have loose wires or the switch itself is bad.
I believe you are correct. Everything else electrical is working better with the new belt, just the switches that suddenly started acting up. Just confused why it started happening once there was a better belt on the alternator pulley.