Grass spawning in Mushroom Biome

In a Mushroom Fields biome, grass generated when it shouldn't have, as only mycelium and/or dirt is supposed to generate there naturally

STEPS TO RECREATE:

1. Make a world with the seed: 2076827737
2. Go to coordinates: X:2963 Y:71 Z:3143
3. You will be able to see grass spawn in a mushroom biome