Didn’t know that. But your information inspired me for further checking it.
I assume that pressing CTRL+C during sudo prompt would result in 1 fail attempt record in
faillock, same as typing incorrect password or empty password. To be lock for 15 minutes we need 3 incorrect attempts.
Now I’m playing around with sudo prompts after
sudo gedit with different “methods” like interrupting it with CTRL+C or typing incorrect/empty password during first attempt and I made it to this issue only once after pasting empty password, next correct one was not accepted and “Sorry, try again” message appeared. After 3 attempts I did
faillock --reset and it worked flawlessly.
Now I’m trying to do it again, after fresh reboot and everything works perfectly even with these “pam” messages in logs (they appear after unsuccessful password in sudo prompt, but in next attemp correct password is accepted so it is as it should be).
but I can log in, and i can use sudo switching to TTY.
I can do it too when error occurs. Maybe there is something wrong in GNOME?
For me it just happen only single one time from time to time (few days) and after
faillock --reset problem is gone.