I am unsure if the way I died caused this but I died by hitting the ground too hard while flying with my Elytra. When I came back to where I died I picked up all my items besides anything in the armor slots (Helmet, Elytra, Leggings, and boots) just disappeared, they were all netherite . The map in my offhand was still there. I was in multiplayer on my world when this happened, I had operator perms (I know that when visitors die nothing drops). I had died on this world 2 times earlier that day (single player) and was able to get all my stuff back. I did check that none of my friends on my world picked my stuff up as well.