Well, that's why I said public. Personally, I don't think release notes https://help.openai.com/en/articles/6825453-chatgpt-release-... hinted at any such thing, and I think quantization is more likely than distillation.
Though this theory has the defect that GPT-4 is, I think, more expensive than GPT-3, but as I recall it was considered unlikely that GPT-4 is larger than 175 billion parameters. Not sure.