Weird terrain generation on surface

**Describe the bug**
Sometimes I don't really understand the terrain generation of this one but it's kinda somewhat convincing:)

**Screenshots**
https://private-user-images.githubusercontent.com/204191710/597705724-9c5533c8-3028-4794-b87b-6b21ad4baad1.png

**Additional context**
https://github.com/fredboy/cavedroid/discussions/81#discussioncomment-17051235