That would make sense, because about a year ago I had to deal with an ammonia spike (one of my fish even got some ammonia burns)Stunting has more to do with lack of enough and large enough partial water changes, than actual tank size.
Of course metabolic waste like nitrate, and other organic compounds builds up faater in a small tank, turning tank water into an organic hormonal soup which hastens stunting , but that can be mitigated by large frequent water changes.
In a 10 gal tank, 50% every other day water changes for gold fish is not overdoing it.
I was able to do enough water changes to save the fish. And thankfully the burns went away. I need to be more diligent to make sure that doesn't happen