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SUMMARY


STEPS TO REPRODUCE
1. launch Krita preferably using 2 monitors. Running Krita on a single monitor and other desktop apps on the other monitor
2. Setup the default painting workspace and select a brush that has pressure sensitivity enabled. While painting the the paint is applied depending on the pressure, gentle at first and then slowly build up paint.
3. Click some app on the other monitor and type something using the keyboard into the other app

OBSERVED RESULT

Navigate back to the Krita and start painting. The brush's pressure sensitive is lost and it starts painting with 100% pressure, meaning it draws a thick line with paint. After few seconds it resets back to the prior settings. A workaround is to click some other tool, back to Brush and continue working in Krita.

EXPECTED RESULT
Brush should retain its current settings (pressure sensitivity)

SOFTWARE/OS VERSIONS
Windows: 
macOS: macOS Big Sur Version 11.7.10 MacBook mid 2014. Intel chipset
(available in the Info Center app, or by running `kinfo` in a terminal window)
Linux/KDE Plasma: 
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION
I'm also using a Wacom Cintiq as the primary display.