Grass blocks can generate underwater

The bug

Grass blocks can be generated underwater.

Reproduce

• Enter the following seed and coordinates.

  Seed: 7394312107885230768
  Coordinates: /execute in minecraft:overworld run tp @s 133.70 61.00 -334.78 -198.75 45.60
  

  → Notice how grass blocks are able to generate underwater.

Expected result

Grass blocks should not be generated underwater; instead, dirt should be generated.