I am experiencing similar problems
(Pixel8Pro | UD1A.230803.041.2023103100. Using Standard Launcher in all user profiles).
The main profile is very laggy, after a restart it works fine until I log into the second user profile and use it for a while. If I then switch back to the main profile (both when the second profile remains active in the background and when it is ended with end session), the following problems occur regularly:
- Frequently: Unlocking with biometrics does not work
- Often: Lag when unlocking (lock screen takes approx. 3 seconds to disappear and release the home screen)
- Almost always: Back button or recent apps button do not work
With the exception of biometrics, the problems only occur in the main profile.
In my case the problems - unlike those described by n0body - occur regardless of whether PIN, PIN scramble or password is used (I have tested each setting in all profiles).