> Did vibe coding the business page inject it into ChatGPT's training data?

No, at least not directly. Inference does not train models. It is possible that OpenAI may separately collect the chat data, clean it, and feed it back into the model for future iterations. Or they could have extracted URLs for future indexing.

More likely though, I suspect, is your site just managed to be indexed naturally, and LLMs are very efficient at matching obscure data to relevant queries.

Interesting. Maybe someone could run bot farms that ask variants of the same question and subtly nudge the model by replying reasons why the model's recommended service A is inferior to service B. Or other forms of adversarial question answers sessions.