Describe the bug
Pools of dragonrot/midnight solution/liquid crystal replacing parts of the ground or buildings... chunks of mushroom or pyrite inside of a house.. this really shouldn't be happening and breaks a lot of immersion

To Reproduce
Go to pretty much any spectrum:city_below. Look at how some feature placed by a biome has overriden part of a house or other structure.

Expected behavior
The city would not overlap with any worldgen features, causing said feature to not get placed. If this is not possible, then it should instead have higher priority than these, the CITY being the one to overwrite the feature.

Screenshots
You've all seen this countless times, i don't think a screenshot is necessary here :P