Already able to see some very minor burn in after playing a game for 10 hours that has a fixed UI. Only visible on dark gray screens. I was at 100% brightness =/, went down to 30% as suggested by others.
That's just image retention no oled is going to burn in after 10 hours. It will go away with varied content.
I've gamed for 1000's of hours (some at 100% for hdr the rest at 80%) on my 2019 lg c9 and have zero signs of permanent burn in.
Almost all panels that exist today are just LG display panels and for the most part should have similar burn in protections.
If you're talking about a panel pre 2018 then yes burn in was a bit more likely and even I, with the same game I've put thousands of hours in on my 2019 c9, saw permanent burn in on my 2016 after just 3 months and maybe 300 hours of said game.
Today its very very difficult to burn in your screen unless your absolutely careless or are purposefully disabling protections built in and enabled by default.