Two things to pay attention here. Cerebra’s can only run a small version of GPT5.3, because why else would they run only a smaller model?
Also, where is gpt-5.3-codex on azure? Opus 4.6 is available since the launch in both azure and google vertex. Codex is nowhere to be seen.
I mean, is it possible that they could run the full-size model on it, but doing so on the smaller amount of hardware that they have is a worse trade-off for now, and it's better to run more of the smaller model so that it can actually provide capacity to people?