I believe this is caused by Microsoft changing the position of the badge on taskbar icons in win11. Apps sometimes put the icon in the shortcut icon and then request an overlay icon over that.
Earlier versions of Start11 painted it at the bottom as Windows 10 did but this was addressed recently to be at the top as 11 does. The 1.28 beta of Start11 resolves this and it should be updated to release version later next week.
