> Advertisers do not have access to your chats, chat history, memories, or personal details.

...but thanks to the method OpenAI are using of showing ads based on conversation topics, they do know that user <a> was talking to ChatGPT about topic <x> on one day, topic <y> on another, and topic <z> on another day.

That's still a form of chat history, even if it's vague.