Bug description:

When generating a world using the caves buffet type (any biome), stone and underground resources are replaced by netherrack. Water at sea level is replaced by lava, although small underground pockets of water spawn beneath this. This bug only occurs in snapshots 20w21a and 20w22a.

Reproduce:

To reproduce this bug, generate a caves buffet world and select any biome while playing on snapshots 20w21a or 20w22a.