There is no “I don’t know who owns the IP” defense: the image has a copyright, a person owns that copyright, publishing the image without licensing or purchasing the copyright, is a violation. The fine is something like $100k per offense for a business.
This is why I'm gnashing my teeth whenever I hear companies being fine with their employees using Copilot for public-facing code. In terms of liability, this is like going back from package managers to copying code snippets of blogs and forum posts.
Why this restriction on public-facing code? Are you OK with Copilot being used for "private"/closed source code? I get that it would be less likely to be noticed if the code is not published, but (if I understand right) is even worse for license reasons.
I have lower expectations of the rigor with which companies police their internal codebases, though. Seeing Copilot banned for internal use too is a pleasant surprise. Companies tend to be a lot more "liberal" in what kind of legal liabilities they accept for their internal tooling in my experience.