A little over a year ago, in another thread (https://forums.opensuse.org/showthread.php/511266-Plasma-5-frustrations-runnenth-over?p=2740410#post2740410) I whined and complained (amongst other things) that:
Login box (sddm) appears on all four monitors, yet typing in password is inputed into the login box on monitor 2 … manually clicking in the login box on monitor 1 (or any other for that matter) changes the focus of where the password is entered
I’d been waiting on sddm v0.14 for a while now (I was vaguely aware that there was a hold up in factory for some reason or other), and it has indeed brought about a correction to that one little behaviour. (In other words, when you start typing the password, it is inputted in the pasword box on monitor 1 (primary monitor), as opposed to that which would be displayed on a non-primary monitor (which might not even be powered on). Yeah! lol!
Just thought I’d share the good news (however trivial it may be),