https://help.openai.com/en/articles/8912793-c2pa-in-chatgpt-...

It doesn't mention the new model, but it's likely the same or similar.

I just checked several of the files uploaded to the news post, the "previous" and "new", both the png and webp (&fm=webp in url) versions - none had the content metadata. So either the internal version they used to generate them skipped them, or they just stripped the metadata when uploading.