All KB articles (including tech-only articles) are sent to the OpenAI API so that we can use it to generate responses. However, nothing is going to be sent to a customer unless a technician decides to do it. There is no risk of leaking any private information without an explicit consent from one of your employees.
Also, we do the same for any external web pages that you decide to index. We send them to OpenAI for generating additional context information.
Open AI doesn't store any information on their servers (or so they claim). Nothing that can associate a KB article with your company name or other "identifiable" info, unless you actually have this info in the KB article text.
Customer's data is always isolated from each other.