[MC-125858] Grass / flowers / snow / trees are placed incorrectly in Superflat World

Grass / flowers / snow / trees are placed incorrectly in superflat world.

Flower Forest

minecraft:bedrock,63*minecraft:dirt,minecraft:grass_block;minecraft:flower_forest;biome_1,decoration,lake,lava_lake

Mushroom Fields

minecraft:bedrock,63*minecraft:dirt,minecraft:mycelium;minecraft:mushroom_fields;biome_1,decoration,lake,lava_lake

Bamboo Jungle

minecraft:bedrock,63*minecraft:dirt,minecraft:grass_block;minecraft:bamboo_jungle;biome_1,decoration,lake,lava_lake

Linked issues

[Mod]Les3awe 2018-02-18T14:29:46Z

This issue relates to MC-610.

[Mod]Les3awe 2018-02-18T14:33:08Z

@unknown say:
Super flat behaves different so make another ticket for that.

In 1.16.1 and 20w29a.

How is this not just a duplicate of MC-610?

I agree, both MC-129153 and this should be merged to MC-610 because I don't see any difference between them.

[Mod]Les3awe 2021-05-19T14:48:55Z

MOJANG decided to split the issue.