Keyboard layout reverts on window focus

Manjaro KDE user for 3 years now, one of my favorites distros when my RAM allows it.

I use 2 different layouts, one of them being English US.
Probably after a played a bit with the settings for a specific use case I had about one week ago, and after reverting back to my previous settings, something is definitely broken.
The layout keeps setting itself back to US on certain apps, even when I remove it from the list.

Layouts seem to be linked to the apps I use, even though my layouts are set on global setting in the GUI (manjaro settings manager). Using setxkbmap does sometimes work, but most of the times is reverted right back.

I tried to remove all but one layout (the second one), but us keep coming back when I focus certain windows.
~/.config/kxkbrc shows the second layout alone, so the settings seem to be applied.

Not sure what causing the revert, but my guess is that somewhere, a part of KDE saved layouts per application/window, and loads it when changing focus (this part I have no clue why), cannot find the corresponding layout and end up adding back the missing one.

I’m also (sometimes) using fctix, though I don’t think it is related, as I did not enable fctix input methods in my testing.
I’m not using ibus.

Does anyone know what could be the underlying issue ?
I couldn’t find the file(s) containing the layouts per window, I assume it is somewhere and deleting/resetting it could “solve” my problem.