Sweet berries don't generate on podzol or coarse dirt, despite being able to be placed on those blocks

To reproduce, use the Overworld preset, but convert the biome to giant tree/spruce taiga. When the ground is grass, sweet berries will spawn, but only on grass. When the ground is podzol or coarse dirt, sweet berries will never generate. This is apparent in normal worlds as well, as sweet berries will generate very close to podzol/coarse dirt but not on it.