My skin changed to kai when i used forge to play with mods

I wanted to play the games with mods, then, i downloaded the forge and some mods. Everything is working fine, but for some reason my skin changed for Kai (Even if i have my own skin selected or another one). This only occurs when i play with mods, when i put the default version of the game, it works normally. i tried many different things, but nothing solves the problem. The version i'm trying to play is 1.20.1 (can't define this version for the issue)