One example that I hate on iOS: the notification/lockscreen curtain is supposed to cover the content as it slides down. That’s what a curtain does, this has been the language for years. Now the curtain is transparent, so it can’t cover the content behind. How does the content disappear then, as you slide the curtain down?
… it doesn’t. Icons do a buggy looking animation crashing toward the user and through the screen, and if it’s an app there is just no transition. You can check by sliding the curtain down slowly and then letting go.