Hey all, I wish I knew what logs to give you but if you ask you will receive. I kept thinking this was a cable issue but it does seem to be a software based issue, either arch or KDE. I'm running nvidia hardware with un used intel integrated graphics. I have two monitors and after an update but I'm not sure which one cause I went a couple days without using the second monitor, I can now no longer put windows there, without them snapping to the main monitor. Interesting if I position the secondary monitor above or below instead of left / right, window border disappear and kwin keeps crashing and I wouldn't want top/bottom alignment anyway.
Here's a video of this behavior , xorg conf, xrandr -q, /etc/X11/xorg.conf
EDIT: I removed my xorg conf file, and although I don't understand what's going on fully behind the scenes, KDE seems to now be taking over the window management and it just works.