it's a feature if the green dot is in the corner , it's a notification to let you know your camera is being used , so as to warn you if you do not know an app is accessing your camera or mic
I find it annoying too... It would be nice if you could disable it by secure authentication or something. You know, a disable option where you need to enter your Samsung or Google account password to authenticate that it's you choosing to disable it.
I never thought about the possibility of screen burn... I use Samsung Health's snore detection so it's probably flashing away all night for me too! I hope I don't end up with burnt or damaged pixels due to prolonged use. 😕