and why should that be solved by "made by AI" being mandatory label when pretty much all of coding now involves it
Involves and made only by, are 2 different things.
I use agentic coding in my daily work. I do make mental model of the code I write and I also test the code, exactly the same way, as when written completely manually.
i ban the use of AI generated code in my projects. at least one of my projects uses libxml and someone could propose to switch to an alternative. a label would make it easier to avoid this library.