And someone accepts it. Even if suggesting derivatives of licensed code is not a license infringement, then Copilot sure is a vector for mass license infringement by the people clicking "Accept suggestion". And those people are unable to know (without doing extensive investigation that completely nullifies the point of the tool) whether that suggestion is potentially a verbatim copy of some existing work in an incompatible license.
If I suggest whole lines of dialogue to you, the screenwriter, did I write those lines or you? If you change names in those lines of dialogue to fit your story, do you now gain credit for writing those lines?