Ask HN: Why would a company ban ChatGPT?

I work for a large corporation, that I don't feel comfortable naming, but they sent out an email to all 160K employees forbidding anyone from using Bing, any ChatGPT, GPT of any kind on company computers for security reasons. They provided no explanation other than saying "for security reasons". Does anyone have any idea what it is they are worried about? I don’t see where it could be an issue. How would it be any less secure than a regular search engine?