Palmey96

I also had this issue in the most recent version, 1.21.90. I had a shield enchanted with Mending and Unbreaking III and combined it with an illager banner in my 2x2 crafter. Instead of retaining its enchantments and also being decorated with the banner, the shield was decorated with the banner but the enchantments were removed.

I also had the issue of elytra and armor disappearing on collision death! Back in April I had just fully enchanted my set of diamond armor and elytra and I decided to try and fly down my mine shaft staircase, brilliant idea I know. I thought it could be a quicker way of traveling down there and that the worst that could happen was I lose a few levels to dying in a confined space. When I inevitably did die due to flying into the ceiling, I came back expecting to collect my items, but only the stuff in my inventory was still there. I dug out the blocks in the ceiling around where I died thinking my armor and elytra might have gotten stuck in the blocks above the mine shaft, but they weren’t there. My helmet, elytra, leggings, and boots were deleted when I died. This was in a single player world running the most up to date version of minecraft at the time, not experimental. I also second the suggestion that the bug of worn items being deleted on death while running into something while flying with elytra should be in a separate bug report because it is different from invisible/floating/not able to pick up items after death in a multiplayer world.