I don't mean "hard" in the sense that it can easily solve novel problems that no living human knows how to solve, although any "general" intelligence should certainly be capable of learning and making progress on these just like human would, but without limitations of human memory, attention span, relatively short lifetime, and other human needs.
I mean "hard" in the sense that it can reliably replace the best software developers, civil engineers, lawyers, diagnosticians. Not just in economic sense, but by reliably matching the quality of their work 100% of the time.
It should be capable of methodically and reliably arriving at correct answers without expert intervention. It shouldn't be the case that some people claim that they don't know how to code and the LLM generated an entire project for them, while I can confidently claim that LLMs fall flat on their face almost every time I try to use them for more delicate business logic.