Emptying composters while holding equippable items duplicates them
How to replicate:
Place composter
fill all the way up with composter-able items until the bone meal texture appears
hold a helmet in your main hand
interact with the composter
the helmet should be in both the player helmet slot and the hotbar. The hotbar helmet can’t be moved, and will disappear once you do other stuff.
I think it relates to MCPE-65815