Minecraft skin will revert to default skin when restarting the game

I had no problems with my skin, I had had the skin for years but when the update came in 1.21.20 my skin was reset, I was surprised the next day it was gone again and was a standard skin, I tested it, recreated it and saved it Everything is ok but as soon as I restart the game it is gone again and becomes a standard skin. I have never had any problems and since the update came in 1.21.20 it hasn't worked. I don't have a Minecraft account to log in to. How can it happen? That's what happened, fix it, I'm really pissed off, that's why I spent money on it and since 1.21.20 came out I had no desire to do it anymore. Where 1.21 came out, everything was still there, my skin too, but the update 1.21.20 that came out was all gone, please remove it The update would be a great help to me even without a Minecraft account, thank you