The bug: If a cave system generates under an igloo, it leaves the igloo floating, and can also make it generate without the basement while still having the trapdoor.

Steps to reproduce: Use the seed (5019295528723431157) and go to the coordinates (/execute in minecraft:overworld run tp @s -2944.95 124.08 8498.91 688.50 54.33) in the attached screenshot.

What I expected to see: Either an igloo on solid land or a floating one with a basement.