Just because the public can't come to a definition, doesn't mean that a small group can't come to consensus about what it is with regard to what they can police. It may not match your definition, but it could be well defined.

That said, I have no idea if they have done so.

I think people tend to categorize obvious exaggerations as fake news but in reality fake news is much more subtle than that.

If you look at the criteria they’re using, “fake news” isn’t one of them.