Iron and Snow Golems don’t attack untamed zombie horses, skeleton horses and zombie nautiluses, as well as camel husks that never had a player riding them, this is inconsistent in how the game treats undead mounts, as they are considered monsters
Steps to reproduce the issue:
Summon one of the two golems near one of the above mentioned undead mounts
Expected result:
The golem should attack an untamed undead mount
Actual result:
The golem ignores it as if they are regular passive mobs
They are passive, golems don't attack passive mobs