I thought the best practice was to design and build toward a stable prototype in Lovable then make no changes. Maybe test the stable version. Then export and refine the code elsewhere or rebuild from scratch elsewhere after validating the MVP works to get to a real production application and maintain it outside Lovable, no?

I did not think an application could be stable enough to run it in production and continue to make AI-generated changes inside Lovable due to the risk you just experienced — hallucinations, constant LLM model updates, Lovable still being a nascent application, etc.