It contains a google library, but can't find what exact library they are referring to, as the link they've provided is dead.

EDIT: Found it in an old commit from around that time the comment was made https://github.com/massivemadness/Squircle-CE/blob/1818d3904...

A googleplay "appupdate" library, I don't have knowledge about App development, but I don't see how this library is needed in the fdroid version?