On the Pixel 6, if you set it to stop displaying over other apps, it resets itself to allow it after each call. When that happens, you get the little bubble/circle icon of the person you're talking to, floating around the screen. It's quite annoying. Also, and I'm not sure if this is specific to the app, but the notification message, when you miss a call, has an option to call back. When you press it (on the Pixel 6), it doesn't do anything but clear the notification.