Dunning Kruger is when you have such a limited amount of knowledge that you overestimate your own competence.
Dunning-Kruger is about unshakable overconfidence, as in believing you know more than real experts. Flat earthers scoffing at astrophysicists would be a good example. So many people who actually know what they are talking about have explained why Kramnik is wrong about his claims, but he dismisses them all. Thats Dunning-Kruger.
Who? Name me these people. Nakamura? Or maybe you're talking about chess.com reports? Kramnik has reviewed them and asked some experts to review them. Everyone agreed that these reports are just circus.
If Kramnik has a problem with Chess.com, he is free to stop playing here. If he has a problem with online chess in general, she should stop playing online. He can restrict himself to OTB tournaments, he can complain about FIDE not providing enough security against cheating. Unfortunately what he cannot do is stop time, reverse the aging process, prevent his skills from slowly declining, and from losing to talented younger players. Welcome to the real world.
How his skill is declining and how he loses to young talents you can observe in recent real-world match vs Jospem (Clash of Blames, Aug 18, 2024 – Aug 21, 2024). All what Jospem defenders can now do is to whine that increment was 2 seconds not 1 second lol.