After notification is replied to from the notification bar there's a black line that goes quickly from the top of the screen to the bottom and sometimes it causes the phone to freeze. The part where the camera is on my Samsung Galaxy S10 Plus becomes all black instead of blending with the color of the app or a home screen wallpaper. This has been happening since Android Pie. I've included a slowed down version of a conversation, an example of this happening in Facebook Messenger as example. A GIF.
Hey @Adem0! Is this happening with any notification reply and with any app? Try doing a Soft Reset of the phone by holding the Volume Down as well as the Power buttons for 10 seconds and see if it helps. Is the phone fully up to date too?