Items dissapiring upon various deaths

I originally found this glitch when my friend jokingly maced me, when I went to collect my stuff all items I had equipped (netherite armour, elytra and shield) had disappeared despite all other items staying, none of this was low durability and it all had mending and unbreaking 3, with some pieces having thorns 2 alongside other enchants specific to the piece of gear, later, my friend had also used the elytra to fly around an artificially dug cave but died to kinetic energy, upon returning, the exact same items were lost.

After this we copied the world and replicated him using the mace on me, I lost the equipped items, then I tried dying of kinetic energy like he did but I didn't lose my stuff, this hints that's the deaths where this glitch happens could be specific to the player.

Finally, we tried replicating this in a creative world, I went into survival, got mace smashed, all my armour was there.