GPT-4 starts many responses with "As an AI language model", "I'm an AI", "I am not a tax professional", "I am not a doctor". GPT-5 does away with that and assumes an authoritative tone.

That makes fundraising easier, by increasing the appearance of authority and therefore coming off as a "better" model. In the elo ratings I'm sure GPT-5 is doing better because of the clear push back against these LLMs as ways to "cheat" without understanding and to flood propaganda -- better not to mention it.