Adult piglins will "give" the player soul speed boots by throwing it down and immediately picking it up again. Expected is that only baby piglins do this.
Linked issues
is duplicated by 6
relates to 2
Comments 4
As a workaround, giving the piglin gold boots before bartering does not allow them to pick up the iron boots.
This is NOT intended behavior. I recommend Mojang fix this bug by simply removing all armor from the table. It's not something a piglin can actually trade due to game limitations.