Whenever I invoke KRunner using the default key-bind (Alt + Space) it opens in my secondary monitor, even if the cursor isn't located in it, while in X11 it opens in whatever monitor my cursor is located. I must note that even if I make it my primary monitor the behaviour is the same, my "primary" monitor is using a DisplayPort while my secondary is using an HDMI port; for the sake of simplicity I'll call the one using the HDMI port as my "secondary" monitor.
STEPS TO REPRODUCE
1. Open KRunner
KRunner opens, but in the secondary monitor.
For KRunner to open in the monitor where the cursor is located.
Linux/KDE Plasma: 5.16.15
KDE Plasma Version: 5.24.3
KDE Frameworks Version: 5.91.0
Qt Version: 5.15.2
*** This bug has been marked as a duplicate of bug 427069 ***