Summary: Passengers on an ender dragon ride too high. This bug has been fixed for April Fool's Snapshot 2022.
Steps to reproduce:
/summon ender_dragon ~ ~ ~ {Passengers:[{id:"minecraft:iron_golem"}]}
Observed results:
Expected results:
MC-259576 Passenger's riding position is too high on a phantom
MC-260086 Entities riding sniffers are positioned too low down
MC-80876 Entity riding vehicle has always same offset