It's only 2022 ( 1+ years after the release), and my Samsung galaxy S21 screen gets its first burn in mark.
I got the mark as a residue of the camera usage indicator ( a green circle that appears in the top right of the screen for just a moment to indicate that the camera or mic are being used)
I see this very problematic because while I hit 6h screen on time almost daily I don't do lots o video calls or record long sessions of video to trigger that indicator.
So if a thing that only appears from time to gets the screen to burn what will happen if someone uses an app that have a huge green icon or button in the UI.
Unfortunately I bought the phone on second market so I have no warranty to make them pay for this mistake.