Hasn't that been a thing of the past for a while now?
I just had to double-check my dock to even find a non-squircle icon, and there's exactly one in mine: Spotify. (Two if we count "Disk Utility", which has a disk icon overlaid at the bottom right but is otherwise a squircle; three if we count "Activity Monitor", which shows a CPU histogram.)
I agree that it's not a great change. In my view, it makes app icons much harder to distinguish by shape alone, and increases reliance on color (which, at least on iOS, I don't have displayed anymore on most of my home screen themes).