When I switch tabs, some apps may change the window size when I switched it. The window size is bigger than before, and when I switched other apps, it will be normal. For me, Firefox Nightly and Steam may cause this issue.
I'm using Groupy 1.2.5 and Windows 10 19H1 Build 18362.267, Firefox Nightly 70.0a1(2019-08-11).
Like this video: https://streamja.com/rKng