Since copilot famously outputs GPL covered code… no, we have proof they didn't do that.
If you write some code and release it under the GPL. Then I take your code, integrate it into my project, and release my project with the MIT licence (for example), it may be that Copilot was only trained on my repo (with the MIT licence)
The fault there is not on Github, it's on me. I was the one who incorrectly used your code in a way that does not conform to the terms of your licence to me.
I don't think the fact that Copilot outputs code which seems to be covered under the GPL proves that Github did not only crawl repositories with permissive licences when training Copilot.