The Bug:

Decorations can replace parts of igloos.

Just for clarification reasons, decoration blocks are blocks such as grass, ferns, seagrass, etc...

Here is an example:

Seed: 2271668349178406851
Coordinates: /execute in minecraft:overworld run tp @s 27219.50 63.37 4203.19 158.03 13.60

Steps to Reproduce:

1. Generate a world with the seed provided above and teleport to the given coordinates.
2. Look closely at the generation of the igloo and how nearby decorations intersect it.
3. Take note as to whether or not decorations can replace parts of igloos.

Observed Behavior:

Decorations can replace parts of igloos.

Expected Behavior:

Decorations would not be able to replace parts of igloos.