Ocean Monument Generation Overwrites the Surrounding Terrain

When Ocean Monuments generate in 1.18 Release Candidate 3, they delete surrounding terrain in a cube around them. 

What I expected to happen was...:
Ocean Monuments would generate integrated in the terrain

What actually happened was...:
Ocean Monument generation overwrites terrain generation and forms weird borders

Steps to Reproduce:
1. Open a 1.18 Release Candidate 3 World
2. do /locate monument 
3. teleport/travel to the monument to see the generation bug