The bug
Some naturally spawned animals always spawn with the default color / variant.
Horse: white
Llama: creamy
Sheep: white
Rabbit: brown
Parrot: red
Spawning them using spawn eggs or /summon
is not affected. Apparently some values are still random, like for example the health of the horses.
Does not affect superflat worlds.
Linked issues
is duplicated by 1
Attachments
Comments 1

Apparently affects llamas and sheep as well, included them therefore