(I'm trying to make sure if this is WAI or not.)
See summary.
Affected mobs:
Pufferfish hurt any mobs that go near them except the player
Llamas attack players (after being hurt by them) and wolves (See also: MC-109384)
Wolves, Polar Bears, and Iron Golems respond aggressively to (accidentally in the case of polar bears and golems) being spat on by llamas.
Ocelots attack chickens
Wolves attack sheep and rabbits
Linked issues
is duplicated by 3
relates to 2
Attachments
Comments 5
This is probably intentional because difficulty doesn't affect the damage dealt from mobs to other mobs.
Can confirm in 1.17.1. However, this is working as intended as per the resolution of MC-227058.
Add that Fox still attack other mobs.