Comment by Leynos

If you're an API customer, you can pin to a specific dated snapshot of the model.

See the "Snapshots" section on these pages for GPT-4o and 4.1, for example:

https://platform.openai.com/docs/models/gpt-4o https://platform.openai.com/docs/models/gpt-4.1

This is done so that application developers whose systems depend upon specific model snapshots don't have to worry about unexpected changes in behaviour.

You can access these snapshots through OpenRouter too, I believe.