Copilot sometimes reproduces code verbatim. You can't use open source code except under the terms of the license. Authors whose code may be reproduced by Copilot need to grant a license to downstream consumers, and republishers of Copilot-generated code need to adhere to the terms of that license.
Copilot is inserting ticking time-bombs into its users' codebases.
For a great deal of copilot insertions, it's like the equivalent of me writing the sentence, "the man gasped in surprise" in a novel I'm working on. Yeah maybe that sentence came from somebody else's novel, but you can find the same damn sentence in a thousand other books/papers/etc as well.