The Bug:

Bushes cannot be replaced by trees or mushrooms.

This is because bushes aren't part of the "#minecraft:replaceable_by_trees" and "#minecraft:replaceable_by_mushrooms" tags.

Steps to Reproduce:

1. Place down a bush and open the F3 debug menu.
2. Observe if the bush has the "#minecraft:replaceable_by_trees" and "#minecraft:replaceable_by_mushrooms" tags.

Observed Behavior:

Bushes cannot be replaced by trees or mushrooms.

Expected Behavior:

Bushes would be able to be replaced by trees or mushrooms.