I'm sure everybody can recall Prax's confession to the free navy:
“The thing you need to understand,” he said, an irrational, intoxicating courage blooming in his heart. “Biological equilibria? They’re not straightforward. Never.” “Equilibria,” the man repeated. “Yes. Exactly. Everyone thinks that it’s simple. New, invasive species comes in and it has an advantage and it outcompetes, right? That’s the story, but there’s another part to that. Always, always, the local environment resists. Yes, yes, maybe badly. Maybe without a clear idea of coping with novelty. I’m not saying it’s perfect, but I am saying it’s there. Even when an invasive species takes over, even when it wins, there is a counterbalancing process it has to overcome to do that. And —” The tall man was scowling, and his discomfort made Prax want to speak faster. To say everything he had in his heart before the hammer fell. “And that counterprocess is so deep in the fabric of living systems, it can never be absent. However well the new species is designed, however overwhelming its advantages seem to be, the pushback will always be there. If one native impulse is overcome, there will be another. You understand? Conspecifics are outcompeted? Fine, the bacterial and viral microecologies will push back. Adapt to those, and it’ll be micronutrient levels and salinity and light. And the thing is, the thing is, even when the novel species does win? Even when it takes over every niche there is, that struggle alone changes what it is. Even when you wipe out or co-opt the local environment completely, you’re changed by the pushback. Even when the previous organisms are driven to extinction, they leave markers behind. What they are can never, never be completely erased.”
My question is that it seems to fall flat with the existence of the gate builders in the same fictional universe. I'm pretty sure they've remained unchanged after every single planet they've terraformed.