player model holding left arm as if its an item

I was playing on a world with two friends and one of them left for a bit, when they came back their player model was broken described as being “invisible” they tried leaving and rejoining several times to fix it but nothing happened, I then suggested changing their skin, when they did it fixed their previous issue but made it so on their end they were holding their left arm as if it was an item in their hand or an extension of their arm. we messed around with it for a bit and eventually they restarted minecraft which fixed it.

they were able to take some screenshots of it but cant send them to me, if I ever get them I will add them.