Everybody can see all skins except me (everywhere and all versions)

Hello, i had this problem for 5 months, i know a lot of players and nobody said nothing about this problem, so i thought that it wasn't a game issue but by computer's. Today I decided to solve it trying to uninstall the game (removing all folders) and reinstalling it but it didin't work... I also started looking for any answers online but they didin't match with my problem or they were too old. I noticed that i can see all skins (mine and others) while using every modpack except the Vanilla modpack, the classic minecraft launcher and SP launcher.