It is also not extraordinary to do that.

I have achieved these results around 2015, sitting at home, relaxed. I was not in a match situation observed by millions. Such a situation can knowingly lead to blunders like Kramniks overlook of mate in 2.

I also sometimes "cheated" by aborting the game when I was tired and continuing it the next day (if at all). That's what the player in a match can not do.

I also sometimes restarted a game at a specific position. Can also not be done in a match. Finally, they used better hardware in these matches. I had eight threads on my old Laptop and I used four of them. The Laptop itself was bought around 2005. Between 2000 and approximately 2020 I trained every day and I was on my peak. I am still around 2400 on Lichess today, without training.

So, I hope it does not sound that extraordinary any more. It isn't. Maybe it is now, but not then.

I do not know the time controls anymore, but I always use the latest Stockfish with all available threads. No opening book, but I do not repeat lines to take advantage of that, because I play to train calculation. I guess hash was the (for my setup) normal 4096 MB.