I have published a LLM-assisted proof of a long-standing problem in convex geometry (70 years) while not being a specialist in convex geometry. I am a scientist and I have education and scientific experience in computer science and systems biology, but I was never a mathematician. So, well, you can definitely work across fields at least.
Do you have a link? I would also be very interested in seeing the prompts, from what I've seen you still need to understand the field, maybe I'm wrong.