It isn't really learning, if it's just regurgitating whole function bodies. I use Copilot a lot, and definitely see whole functions being spit out, that were presumably written by a person somewhere.
I also use Copilot a lot, and while it does suggest large function bodies, I'm not sure that it's "regurgitating" them (though it could be...I don't know). I suspect that it's seen so many function bodies that are similar that it generates another similar output. Like autocomplete in a word processor has seen so many similar chunks of text that it reproduces them based on past experience. I don't know this as a fact, of course. I'm just reacting to the word "regurgitating."
Just did a quick github.com search on that function (with comments) and found around 131 matches. Many without a license. So yes, I believe that it would produce those comments...because it's seen humans repurpose and reuse that code without attribution or license many times.
Definitely an issue...but not as simple as copy and paste.
I definitely agree that we should find out. I've used Copilot almost since its inception, and I've seen nothing like a large copied/pasted function. If anything, it's mostly a single/double line autocomplete based on what I would have written anyway.