I feel uncomfortable that I can't actually verify that this story is true.
Asking Opus 4.7 who the reigning 6nimmt! champion is leads to this article and a warning about a possible hoax
Gemini answers with 3 different champions dating back to 2024 and the list of events that the matches were played at. None of the results mention this guy.
I think this is something we'll start to see which is something like a Mandela-Effect, but from LLM results. When we had deterministic search - everyone could see the same result, but now using LLMs knowledge becomes a training and seeding issue. Two people can confidently be given completely different information, so in both cases perceived as true.