In minecraft:giant_tree_taiga_hills, boulders cover the landscape entirely. They do not appear anywhere else.

This is with the boulder_chance "frequency" option set to 1-in-100000 chunks:

I don't think those are mine.

Edit:

As seen below, It is Repurposed Structures. Link to their github: https://github.com/TelepathicGrunt/RepurposedStructures-Fabric

@magneticflux- Those are boulders from my mod called Repurposed Structures. You can configured or removed them with my mod's config

Sorry for the confusion, I didn't realize both mods added boulders!