e2e encryption, meaning all data is "safe while transferred". The client (Whatsapp) can obviously read the data on both sides - and perhaps sent it to Whatsapp

e2e encryption, meaning all data is "safe while transferred". The client (Whatsapp) can obviously read the data on both sides - and perhaps sent it to Whatsapp servers with e2e as well, so the data is transferred safely to Whatsapp/Facebook, without other eavesdroppers being able to see it :-) My point is, if you don't trust the company that created it, it doesn't matter what technology is uses. So who trusts Whatsapp/Facebook with their private data...?