SUMMARY
If there are atleast two non-overlapping firefox windows open and one of them is active (say right) if tab from other window (say left) is selected in Krunner search results, other window (left) doesn't become active one.


STEPS TO REPRODUCE
1. Open two firefox windows and tile them to left and right on desktop.
2. Make left window active and search something in browser (e.g., search "hello")
3. Switch to right window and search something other in there (e.g., search "world")
3.1. Now right window is active
4. Open KRunner and search "hello" in KRunner
5. Select firefox browser tab (titled "hello") from KRunner search results
6. Here left window doesn't become active one.
6.1. To check which window is active open new tab using keyboard shortcut ("Ctrl+T")

OBSERVED RESULT
New tab was opened in right window, which was still active.

EXPECTED RESULT
New tab should be opened in left window, which should have become active one after selecting search result.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma:
(available in About System)
KDE Plasma Version: 5.24.80
KDE Frameworks Version: 5.94.0
Qt Version: 5.15.3
Display Server: X11

ADDITIONAL INFORMATION
I was first informed about this bug for GNOME extension inspired by this software.
And this I couldn't reproduce this issue on Wayland GNOME on Fedora Linux 35, so I assume issue lies with xorg-server or firefox.