Which I think was fairly predictable.
What wasn't predictable was that someone would ship this Copilot anyway, consequently exposing their company and their users' companies to liability.
Imagine if you hired an intern who was copy&pasting bits of GPL'd code throughout your system. This would not be a good job, it would be something that needed immediate attention from legal counsel and others, and mean reverting every commit the intern from heck made if you couldn't prove convincingly it wasn't tainted. Especially if you're a startup, who needs to assure investor due diligence in good faith that you actually own the IP.
Letting your intern blindly commit to your code base seems like the bigger issue here. The entire purpose of an internship is to learn and to be guided by professionals, not to be treated as a cheap laborer. You don't hire interns, you train interns.
Have you used copilot or are you speculating?
(And people couldn't tell in code reviews, nor on other occasions to see the code, since it's not normal to recognize GPL'd code on sight; everyone just assumed the developer was productive.)
This has not been my experience. I was dropped into the developer team and expected to know the entire tech stack and was not trained by anyone from the company at any point. Have I been bamboozled??