LLMs aren't AI. They are more like librarians with eidetic memory: they can discuss in depth any book in the library, but sooner or later you notice that they don't really understand what they are talking about.

One easy test for AI-ness is the optimization problem. Give it a relatively small, but complex program, e.g. a GPU shader on shadertoy.com, and tell it to optimize it. The output is clearly defined: it's an image or an animation. It's also easy to test how much it's improved the framerate. What's good is this task won't allow the typical LLM bullshitting: if it doesn't compile or doesn't draw a correct image, you'll see it.

The thing is, the current generation of LLMs will blunder at this task.