If ChatGPT ever outputs other user's chat history, the company is as good as dead. If that could be exploited using this technique that is out in the wild for over a year: show me the data.
It is an issue with the company though. I saw that as well. The point is that leaking user data doesn't destroy startups, it barely even hurts well established companies.
Read OpenAI's response to this security issue carefully - it tells you a lot about how they think of being responsible for issues like this. I remember they put all the blame on the open source library, rather than taking responsibility themselves.