why MAGNUS CARLSEN STALLED? what makes a MAN hit the WALL?

for example, little Magnus had:

2356 elo at 13 years old (year 2003)

2856 elo at 23 years old (year 2013)

thats +500 elo in ten years

source: https://ratings.fide.com/profile/1503014/chart

in the past 7 years (2013-2020) he has had an ELO progression of... 0 points.

Possible arguments:

1. Age. Let's say at 22~25 years old your brain is already wired and you can't truly learn new stuff. Counterargument: there are many players who improve after 25.

2. Age + human chess knowledge at the time. In this theory, Magnus learned everything that could possibly be learned at his time, exploiting it to its fullest. Even if human chess knowledge is expanding, he just can't keep up with it, so he will soon be defeated by the next generation.

3. Genetic limitations. Visualization, concentration, pattern memorization... among others, are chess skills that can't be unlimited nor all powerful in our human species. In this theory there's a brain-mind limit to what a white or chinese man can do at chess, just like there's a limit to how fast a black man can run (Usain Bolt) or how hard he can throw punches (Mike Tyson). This would require to study players from many years ago like Jose Raul Capablanca or Richard Réti and check if they could fight Magnus on equal terms if they had the same opening preparation.

Any way, if you think of more arguments please share them with me. In my opinion I think it must be a mixture of everything (age, race, popular chess knowledge at the time, talent, etc...), but it would be interesting to study in which proportion every element plays its part, even if the result is the same = hit the wall. Thank you.