Need help with the mouse stroke stabilizer

I ask because gaming mice, with their special drivers, can cause problems but usually when a graphics tablet is also used, which you don’t have, it seems. So I asked to find out.

Something you could try is to download, Extract and use the Windows portable .zip package to see if it’s better, from here:
https://download.kde.org/stable/krita/5.0.6/krita-x64-5.0.6.zip

There are two other people who report similar problems: