That is what I think either. After the accident, his body is more prone to injury. I do not remember other injuries he had. May be he had none. And after the accident he learned how it is to be "mortal". Now he can be easily injured where before he made some push ups and proceeded match with his head held high. And it influences not only body but also his mind. I bet that deep inside he is frightened. We may say that because of the accident he suddenly aged on 5-10 years. That's a lot.
I don't know if he is "more prone to injury" after the accident and Covid.
Let's recap:
He was still basically on a comeback after 1 1/2 years of absence (if you leave out the isolated tournaments of AE 2021 and Olympics 2021) and had played literally an entire month of badminton: Sudirman Cup, Thomas Cup, Denmark Open, French Open.
We all remember how visibly exhausted he was in Paris after the final of the Denmark Open and said he should not play this tournament. He did play and injured his back. D'uh.
After that, he had a month's worth of break/recovery and won the Indonesia 750 comfortably without dropping a game. In the following week at the Indonesia 1000, he again looked extremely tired but got through a tough match against Lakshya Sen in the first round. In the second round, he has no chance against LKY in the first game and Gill and Morten Frost talk about his condition quite candidly, for example that sometimes the coaches should stop a player from overplaying because the players don't realize the severity of the situation.
As we all know, nobody stopped Momota, he fought - again - until he could barely walk and - again - injured his back, just like in Paris.
Compare to Axelsen:
After the Denmark Open final, he had short stop in Paris, made one swing of the racket, said thank you, but I'm injured/unable to play and went right back to Dubai to recover. The smart thing to do after a brutal month of important tournaments. And he wasn't even on a comeback after an extremely long break, like Momota.
In Indonesia, he didn't gave his all in the first of three tournaments, lost to Prannoy in the second round, but then was ready for the 1000 and the WTF and won both. Once again, the smart choice.
After this year's WC, for which he has surely prepared intensely, he skipped the Japan Open. He probably would've won it anyway, given the quality of the opposition, but he once again did the smart thing and managed his career way in a professional way.
This is not a case of being more injury prone after an accident. It is a case of negligence and stupidity.