You need a system prompt to get that behaviour? I find ChatGPT does it constantly as its default setting:

"Let's be blunt, I'm not gonna sugarcoat this. Getting straight to the hard truth, here's what you could cook for dinner tonight. Just the raw facts!"

It's so annoying it makes me use other LLMs.

Its response is still flattery, just packaged in a different form. Patronizing, actually.

Similar experience, feels very ironic

Curious whether you find this on the best models available. I find that Sonnet 4 and Gemini 2.5 Pro are much better at following the spirit of my system prompt rather than the letter. I do not use OpenAI models regularly, so I’m not sure about them.

That is not the spirit nor the letter though.

That is a good point. I guess the reason that distinction came to mind is that what’s happening here is the LLM trying to manifest its obedience in letter (i.e., by saying it).