They never say what the "natural flavor" is.
A reminder that "natural flavor" doesn't mean healthier or even something you might want over the artificially created flavors. It just means it comes from a natural source and is not lab created.
Castoreum, sometimes used for vanilla and raspberry flavoring, comes from beaver anal secretions. That would be labelled under a "natural flavor" and you'd never be told more than that.
I'll take the artificial stuff any day just on principle there.