Honestly you will probably need repairs to fix it. You can try the apps to help clear it first, but otherwise repair for a new screen should help. You can check with uBreakiFix for walk-in repairs.
I don't have one anywhere near me this started happening about 6 months ago I don't keep my brightness turned up at all and honestly feel like it's a defect never had this problem on any of my Notes and it happened less than 2 years after I paid 950 bucks
I have the same phone. I do not keep my screen saver on and I do not keep phone display on but I noticed my screen saver image is burnt in to my screen as well. This just happened with in the past week or two. 😕😔