One model name can sit in front of several upstream channels. Which one answers is a policy decision, and the policy is the thing worth reading.
Labels are not destinations
A model string is a routing label. Stability, time-to-first-token, authenticity and price may all compete in the ordering. A relay that orders price first makes a different promise from one that orders authenticity first.
On Supesonic, inspect permitted models for your key via GET /v1/models and the marketplace.