Hello! There's a problem with my Nokia 6.1. An unknown transparent window with rounded corners always displayed on the screen. See photos (it doesn't displayed in screenshots) at the Android support site: https://support.google.com/android/thread/18802599?hl=en
Android version 9, security patch level: October 1, 2019. Factory reset doesn't resolve the problem. Also this unknown window is displayed in the Safe mode. It seems to me that the window appeared after the latest Android update (security patch level October 1, 2019).