this is another one for cliff & co.
there used to be this hack which brings back the rounded corners of the main screen´s desktop on certain apple notebook models, which did not have them for some reason. (hint hint)
now i wonder if you we could get rid of those ugly corners on all other systems in a similar manner?
p.s.: i had the idea for this from the current debate about the "orange dot issue" in macOS 12, which shines through in fullscreenmode of your graphics apps during presentations and such - an absolute nogo, dear apple.