I would caution against using the webapp to test the quality of this new model because OpenAI does not indicate which image model and effort is being used to generate the image, to my continued frustration.

That said, I gave it one of my more difficult image prompts and the model now surprisingly passes (without plagiaristic cheating): https://chatgpt.com/share/6aebcbcd-6b8c-83e8-b52b-dbedf20ce4...

I think that particular one would be a prompting problem. Instagrammers and anime artists do left-right two-tone dyes all the time, so left-right two-tone rather than meshed gray blonde would be a reasonable interpretation of "half blond and grey hair" based on representations on Internet collected data.

It precisely matches your prompt, more accurately I think than your expectation which it meets if described accurately:

https://chatgpt.com/share/6aec2ba7-6edc-83ea-9a48-b41b53874a...

That prompt seems almost deliberately obtuse. The natural phrasing would be “greying blonde hair”. If you described someone as having half-X, half-Y hair, I’d expect to see something like that image, too.