SUMMARY

If you have a window focused (if you type on the keyboard the input will end up in that window), and middle mouse click on an other window, the focus will switch as expected.

However if you instead use a tablet and do the equivalent of middle mouse clicking, the click event will be passed to the correct window, but the focus will not change.

This makes it really annoying to use the pen in software like Blender/Krita as you have to first tap with the pen on the window to make it respond to keyboard shortcut.

STEPS TO REPRODUCE
1. Open Krita and draw something.
2. Open a terminal (konsole) and set it to "always on top" and type something in there
3. Use the tablet pen button to pan around in Krita.
4. Without taping with the pen on the Krita window, try to use any shortcuts

OBSERVED RESULT
All key presses ends up in the konsole window, even after explicitly interacting with Krita window.

EXPECTED RESULT
The equivalent of right click and middle mouse click on the tablet pen should focus the window just like it does with the mouse.

This is how it works the Xorg version of Plasma (and also in Gnome X11/Wayland)

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Gentoo/KDE Plasma 5.92.0