The real problem here was quoted as "misdirection of the [whatsapp] users and the public" because WhatsApp stated that there wont be any data exchange between them and facebook, when they were accuired two years ago.
German law says ToS can not contain surprising terms.
That also means if an ad says "we won’t share your data, ever", no ToS change, unless it’s more publicly published than the original ad, and as easily noticeable and understandable, can undo that.
Even people like my mother, who normally has no idea about whats going on, were worried back then but then calmed down by that statement. And the media, where this had quickly became an issue, stopped reporting, because everything seemed to turn out fine.
But now, they broke that promise and altered their product, which now results in those accusations of misdirection of the users and the public. They made that statement, people everywhere became reliant to whatsapp and now everything stated before turned out to be a lie.