Zombie horses and camel husks do not spawn from spawners on Peaceful difficulty.
For comparison, shulkers, piglins and skeleton horses do spawn from spawners on Peaceful difficulty. Zombie nautili do as well, but the conditions for doing so are wrong (see MC-304855). All these mobs, as well as zombie horses and camel husks, can generate as part of structures on Peaceful,* but only piglins do so naturally- this is tracked in MC-186131.
*Zombie nautili do not seem to spawn in ocean ruins on peaceful; see the comments on MC-304858.
To reproduce
Set the difficulty to peaceful
Find an area of grass blocks
Place a spawner on the grass
Right-click the spawner with a zombie horse egg
Set time to night
Observed behavior
No zombie horses spawn
Expected behavior
Zombie horses would spawn
Linked issues
Comments 5
Can confirm.
Zombie horses are checking for both animal spawning conditions:
.is(BlockTags.ANIMALS_SPAWNABLE_ON)as well as monster spawning conditions simultaneously:
.getDifficulty() != Difficulty.PEACEFUL
where as skeleton horses check for their own spawn conditions following purely animal rules and omit the block tag requirement only checking for light levels. Nautilus (both undead & alive use the same method) follow their own spawning conditions, checking for Y level and blocks that either have the fluidtag of “water” or if the block is water
and zombie camels are checking for conditions similar to zombie horses except now checking for the block tag “CAMELS_SPAWNABLE_ON"
Made a report about skeleton horse spawners working on peaceful.
I feel like this is working as intended, zombie horses and camel husks do not spawn on peaceful at all, not even on structures, unlike pigskins. The real issue is skeleton horses spawning just fine, when in reality they shouldn’t.