I seemed to encounter an interesting bug of sddm today. Sddm fails to respond to the ENTER key when I typed the ENTER key after inputting the password to unlock the screen.
The interesting thing is that if I type the password directly and then type ENTER or click the button using mouse, it’s fine; but if I click the input box before typing, then typing ENTER has no response.
The Lock Screen or more correctly the Screen Locking on KDE Plasma has nothing to do with sddm, nor sddm theme. Is tided up to Global Theme. Is you issue using Breath or something else?