Just picked up a Model S Plaid built 5/18/23, running 2023.20.8 firmware. The mirrors will not restore any configured inward tilt when switching to reverse.
When I reverse, I bring up Settings and select Mirrors, then adjust downward and inward tilt to my liking. If I switch to Drive, the mirrors return to their original position. When I switch back to reverse, the mirror only tilt down, but not inward.