If you focus a window on for example the second monitor and have your mouse cursor on the first monitor and open something it will spawn on the "edge" between the first and the second monitor. If you have a window focused on the first monitor and open another window it will spawn under your mouse, but if you are on the other monitor it will again spawn at the "edge". Demonstration (File Size was too big for attachment): https://www.youtube.com/watch?v=q4jNBqiEX8c (I use a Hotkey to open Konsole instances)
I watched the video and the behavior looks fine to me. What exactly is it that you expected to see and what did you see?
I expected, that the window should open on the monitor, where the mouse currently is. But as you can see, it opens on the second monitor, where the current active window is.
please provide output of: qdbus org.kde.KWin /KWin supportInformation
https://paste.kde.org/pr93v94cs Here it is. I did a "| grep mouse" for fun and saw this: Active screen follows mouse: no. I guess that is the value to be changed.
Okay. I found the checkbox for it under Window Management -> Window Behavior -> Focus -> Active screen follows mouse (at the bottom). I will close this issue, because it is no real issue. Just a setting, which is hard to find.