At first I ignored that behavior, but now I respond asking them to refrain, it's ok to tell me they don't know or to tell me a hint they might know even if they don't know for sure, but I have access to the same LLMs they have and I don't need them to help with that. I tell them to just send me what they would have sent to the prompt, and if I need the LLM, I'll do it.

It's especially bad when they have zero idea and try to fake it with LLM.