Screeching, distorting and oversensitive AirPods Pro
I've had what sounds like this problem before, on a previous firmware, and I resolved it by placing them in the case (on charge, I don't know if that made a difference) for at least 5 minutes.
You can't reinstall or downgrade the firmware, but you can try resetting your AirPods Pro.

Place AirPods Pro in the case and close the lid.
Wait a couple of seconds, then open the lid.
Hold the button on the case. The light on the front will start flashing white.
Keep holding the button on the case. The light will go orange. Let go of the button.
Move iPhone near AirPods and tap to Connect.