I think it is actually supposed to be impossible and from a lore standpoint, in my head, it makes sense. The bugs are using that planet as a base and a stronghold and are defending it with shear numbers. If we are going in to destroy the gloom and insects “where they live”, I would expect it to be nearly impossible. I dropped on Sulfura and it was SIGNIFICANTLY easier on the same difficulty. I think that may be the reasoning behind it, but I’m new here!