Yes, it's a risk if you don't guide it well, but you can also manage it pretty ok.

I have a side project that I started in January 2024. Initially, used Github Copilot autocompletions heavily. This year I started using CLI agents (mostly Claude, but others too) to do more stuff. I got to around 100k LoC (sure, it's not enterprise scale, but for a personal project it's pretty big), but I'd argue it's maintainable, it's split into 10 Django apps, that are each pretty self contained, I've done several refactors on it (using AI agents) to make it more maintainable.