Pretty sure most large succesful apps have their own UI and UI design teams. Cant remember the last time i saw anything cupertino in an app. Even Apples own 'Home' app only loosely use cupertino. Id say the most noticable effect is the bottom modal sheet slide up effect. on ios the original screen animates into the background a little bit. Apps that dont implement this can be spotted but thats not unique to flutter at all and flutter even offers a pretty good cupertino scaffold package that does this animation.