I'd have assumed a fixed seed was used, but he doesn't mention that. Weird. Maybe he meant that?

Pure sci-Fi idea: what if actually nothing was changed, but RNGs were becoming less random as we extract more randomness out of the universe?

I bet they did both. If I'm reading the documentation right you have to supply a seed in order to get "best effort" determinism.

https://learn.microsoft.com/en-us/azure/ai-foundry/openai/re...