Custom skins appear to the player wearing it but doesn't appear for the other players

(Illustrated in pictures attached)

I'm the player in black, my friend is the player in diamond armour using a certified skin from the marketplace (which works amazingly well), while I appear as a steve to him (no hate towards my boi)

Additional bug: sneaking doesn't look right in multiplayer, with the body being at a 90 degree angle and the legs bent forward at the same degree the body should've been (received_274486696936030 is my friend's screen while the other ones are mine)