https://twitter.com/moyix/status/1433254293352730628
The Register wrote about it too: https://www.theregister.com/2021/09/02/github_copilot_banned...
They have since moved the bad word list server-side to prevent people from figuring out what's on it, but it's still there. This is easy to verify, just ask it to complete something that would include a banned word; my favorite here is "Israel", and it will just sit there and refuse to complete, either via inline suggestions or in the sidebar view that gives you 10 choices:
https://i.imgur.com/O97YwKc.png
This was what I managed to decode of the list (in ROT13 form to prevent accidental offense):
https://moyix.net/~moyix/copilot_slurs_rot13.txt
No doubt they've added and removed some things since then.