I am running GNOME 3 version 3.36_4 on the FreeBSD 12.2-RELEASE operating system. Shortly after I installed GNOME 3, I started having a problem where the lock screen activates as soon as I login and I can’t unlock it. The problem started while I rebooted the system from a virtual terminal while I was logged in. Someone else I am speaking to on FreeBSD’s forum was able to reproduce the problem.
My best guess: gnome-shell crashed while the screen was locked, so that state is restore on startup.
This on the other hand is impossible to diagnose without further information, in particular as screen locking on FreeBSD is already special (it doesn’t use systemd’s logind).