Like everyone else here of any experience I too have waded through gooey code that was impossible to discern any purpose or design in, because there really wasn't any, after everyone was done hacking on it. But the hacking was still bounded by human speeds.
Our only two options for a code base produced that way would be 1. discard it and start over or 2. hope that the next-generation AIs that aren't just LLMs are able to clean it up, since "automatically cleaning up LLM-generated code bases" is going to be a rather lucrative field. LLMs, no matter how much you hypetrophy them, aren't suitable for coding at scale, and they can't be. Their architecture is just wrong. But that's a claim I only make about LLMs, not AI in general.