John's LG OLED is suffering from the burn-in of channel logos. Leo says that the LG shouldn't have that problem since they use pixel shifting to combat it. It should be corrected by using the clear panel noise option in the settings. Also, use cinema mode vs. vivid or demo mode. That will make the screen less bright.
Burn-in does occur, but it's become less and less of an issue. Most burn-in is image retention that should go away after a few minutes.