There a multide of glitches/bug with the current generation of "Woodland Mansions" in the overworld.

• Generation inside hills, cutting the hillside off and leaving a weird air-gap
• When generating inside of terrain, one terrain block remains ontop of the center stone-fence of the mansion border (see pics)
• Terrain blocks are also kept inside the chest rooms and in one other room (see MC-107558)
• The lowest floor can also generate with holes, due to water & lava lakes being able to generate inside the mansion (maybe able to fix by updating the order in which certain world features are generated)
• Non-Full terrain blocks (grass, etc.) are also able to cut through the base of the mansions. This also seems to be the case with some parts of trees (see pics)

How to reproduce:

1. Locate Mansion by using /locate Mansion
2. Look at the way the terrain interfaces with the mansion in Spectator Mode
3. Teleport to new part of world by using /spreadplayers ~ ~ 10000000 1000000 true @a
4. Repeat