I Found out how to fix the issue!!
I wanna give thanks to @ClockworkOcean for helping me trying to fix this issue!
I made my own system to add the missing skins in the saved file
Basically I check the lenght of the loaded save file and substract it the ammount of skins avaliable. The number will be the missing skins. then i add those skins in the array with a “Do N” and when you go yo the shop its finally fixed!!!