Once a player dies, there's a chance that upon respawning, their arms will stick out strangely. It shows up in all perspectives and was visible to my friends who were playing on Xbox and Windows respectively. Their arms remain like this unless the player re-logs or dies and respawns, but it can sometimes remain after multiple deaths. It's purely cosmetic, as interaction still functions normally, but worth reporting, as it's been around since at least 1.11.4.