The problem arose after installing the system update.
In the image you can see how the window is not generated completely
interesting!
What version of UB are you using? 22.04 ?
What theme are you using? Look in budgie desktop settings to see what is set.
if you resize the window the problem is fixed
I suspect that this will be fixed by an upcoming release of libmutter currently undergoing testing.
You can help testing by following the instructions in that bug report - the package from proposed is called libmutter-12-0
I suspect it may be a theme issue, change the theme to see if the issue continues.