Plants can replace mansion blocks when they are generated

Summary:

It seems that when generated, blocks such as grass and seagrass can be generated for the space of the mansion blocks. They seem to be used as support blocks, which allows them to replace the blocks of the mansion.

Seed: -732078047
Coords: -4771 54 4060
Coords: -4849 67 4072

Steps to reproduce:

1. Find a mansion.
2. Review the perimeter blocks generation at the base.
3. If you have not noticed anything strange, use the coordinates and seed that I provided above.

Observed results:

Plants such as grass are used as foundations for the mansion. While replacing cobblestone.

Expected results:

Cobblestone from the mansion will remove plants such as grass when generated. To prevent holes from forming at the base of the mansion.

Image: