TL;DR
- Strings in the latest Android 15 beta suggest the OS can automatically delete biometrics that aren’t working well.
- Android will delete your face or fingerprint unlock when they aren’t working well and then prompt you to set them up again.
- We don’t know how the OS determines when a biometric isn’t working well or if this feature is even live yet in the latest Android 15 beta, though.
If you’re concerned that might be about to happen you could just hold the power button until it shuts down or reboots, Android always asks for the password at boot AFAIK