SUMMARY
I use  (Sierra Charts free download) in Bottles (Does the same with PlayOnLinux fwiw). These open on another activity. When switching between the activities my Windows which show as forground aren't actually receiving focus, instead the app behind it (which you can't see) receives focus. This then affects items like context menus too, whereby right clicking in dolphin will mean it's context menu is BEHIND Dolphin. Sometimes changing the activity and going back temporarily fixes it. Basically the active window is sent to the back but can receive imput. Closing the Wine Apps and changing activities a few times fixes this bug. 


STEPS TO REPRODUCE
1. Download Sierra Chart or some Windows application that allows multiple windows - OUTSIDE of the APP ie SDI.
2. Open app on another activity
3. Switch between the activities, open Brave, Dolphin etc and the foreground app won't receive input.

OBSERVED RESULT
ZOrder with overall desktop gets messed up. ie Clicking On Telegram on the taskbar will bring a background app to the foreground, yet typing will actually happen in Telegram even though it's behind another app

EXPECTED RESULT
Active / Foreground app should be in focus. Zordering appears to get skewed. It appears to have something to do with Activities and Wine apps. I haven't tested on other Wine Apps. It used to work fine around Plasma 5.23ish. It broke around 5.25.

SOFTWARE/OS VERSIONS
Windows: Bottles 50.1
Linux/KDE Plasma: Arch Linux KDE
KDE Plasma Version: 5.26.5
KDE Frameworks Version: 5.102.0
Qt Version: 5.15.8

ADDITIONAL INFORMATION
Tested on Gnome and DEEPIN on the same Linux installation, Zorder works fine while Sierra is open with those DE's.