Yeah have to agree here, Github Copilot itself doesn't have any first party models they use the frontiers. So, they didn't "train" using public repos but they probably allowed (or didn't prevent) the frontiers from pulling the repos along with the rest of the internet when creating their models.
Is y'alls collective memory so short? Copilot just a few years ago was auto complete on steroids that was entirely first party and trained by GH on users' code.