A surprisingly well researched and explained article on OLED including "burn in" from ARS

It also explains the differences between WOLED (LG) and QD OLED (Samsung and soon a couple of others).

It also indirectly explains why QD OLED is better for sharper text display (different subpixel structure)

It also helps that the author actually worked for one of the display makers at one point.

Nice relatively deep dive regardless.

Why OLED monitor burn-in isn’t a huge problem anymore | Ars Technica