I have the same problem On Win 23H2 (22631.3374) with all optional updates installed.
Fast Startup is disabled and always has been from when I first setup the laptop a long time ago.
LG Gram 17ZB90R
I've had the same issue intermittently. This morning. I powered on laptop and it logged in without my fingerprint or any other authentication. I powered it off. Powered on. Same problem. Repeat 3x. Same problem. Did a restart instead of shutdown then powering back up, solved the issue, but only temporarily as I've had the problem intermittently before as well. Maybe someone will find an answer.
One thing that temporarily solved the issue - restart instead of powering off and back on. When you power off Windows 11 (and maybe Win 10), it caches some information to make the next startup quicker. To clear out this cache, do a restart. I guess MS assumes if you are restarting your computer, you might be having an issue and flushes all info and does not use the caching feature. I usually leave my laptop on at all times and just do a daily restart. But since reading the original poster's issue, I think that for me, the problem may only present only when when powering up from a power off state, and even at that, the problem doesn't present itself all the time. Hope this last bit helps someone deal with the issue, and maybe also helps someone solve the issue.
Rob