When it comes to novel work, LLMs become "fast typers" for me and little more. They accelerate testing phases but that's it. The bar for novelty isn't very high either - "make this specific system scale in a way that others won't" isn't a thing an LLM can ever do on its own, though it can be an aid.

LLMs also are quite bad for security. They can find simple bugs, but they don't find the really interesting ones that leverage "gap between mental model and implementation" or "combination of features and bugs" etc, which is where most of the interesting security work is imo.