The way I see it, if you would use Copilot to completely (or largely) reproduce an existing work (software), then you would be infringing copyright. This is similar to using an AI to largely replicate a piece of music.

If you are using it to mix a snippet of code (from a sufficiently large code base) into a large code base of your own, then you are just remixing. That is not infringement. In music, there are entire genres based on remixing. You could even take it a step further and ask yourself: what is not a remix?