Unlock fail only happens when set virtual keyboard to Fcitx 5 or Fcitx5 wayland launcher. It seems the keyboard is repeating by itself, and get locked after wrong attempts. I see same issues on reddit, no solution for years.
BTW, By disable virtual keyboard, I can’t use input method in Chromium.
I’ve noticed the same, specifically when waking up from sleep. Not always, but not exactly rare. My solution was to open a TTY, login as a different account with root access, and then do loginctl --list-sessions, get the session number I need, then do sudo loginctl --unlock-session with the ID for that session. Then I’m able to switch to exit the TTY and switch to the session that should now be unlocked.