My friend and I have a survival world together, when i left the world i had all my stuff, when I loaded back in the next time it must have failed to sync user data correctly because, when I loaded back in I had nothing. I had lost my 2 maxewd out tridents, maxed out full netherite armor, maxed out netherite sword, a maxed netherite hoe, a maxed netherite shovel, 2 maxed out netherite picaxes, and a maxed netherite axe.