Earlier quoted context omitted.
Adding to this: I run product security for a large enterprise, and I've already gotten the ball rolling on prohibiting copilot for all the reasons above. It's too big a risk. I'd be shocked if GitHub could remedy the negative impressions minted in the last day or so. Even with other compensating controls around open source management, this flies right under the radar with a c130's worth of adverse consequences.
Do you also block stack overflow and give guidance to never copy code from that website or elsewhere on the Internet? I'm legitimately curious - my org internally officially denounces the copying of stack overflow snippets. Thankfully for my role it's moot as I mostly work with an internal non-public language, for better or worse, and I have no idea how well that's followed elsewhere in the wider company.
https://stackoverflow.com/help/licensing
It appears that the code that copilot is using is created under a huge variety of licenses, making it risky.
On the other hand, a small snippet in a function that is derived from many existing pieces of other code may fall under fair use, even if it is not under an open source license of some sort.