Grindylows as monster mercenaries do not gain the damage resistance they should when burrow is used.
That was the point, I believe. Dev nerfed Grindylows in player possession.
Can we just have the move removed from them as mercs? If you set them to ai controlled they wasted their first turn burrowing
Or! You just don't use them?
This isn't a discussion forum, if you don't have relevant information to the bug report then don't post.
They have significantly reduced damage reduction while mercenaries, this is intentional.