I have this same issue. @vready I believe you're correct about this being related to a Yubikey. I have a 2020 MacBook Pro 13" and am using the Yubikey 5 NFC. It doesn't seem to matter which applications are open. Usually I have Chrome running in the background. I get to the login screen after being away from the computer and when I enter my pin, the screen freezes. I end up needing to do a hard reboot to get the MacBook to respond again. I've been testing and it seems that when I leave the YubiKey unplugged and only plug it in to authenticate, things work as they're supposed to.