Nothing changes in normal chat usage
In fact, nothing changes with normal messenger usage. WhatsApp has been sharing data with Facebook since 2016. Many people were not aware of this, but TECHBOOK among others did so Reported extensively about it. In the European Union, data transfer is stricter than anywhere else. For EU residents, everything is the same.
continue reading: WhatsApp accesses this data from your mobile phone
Banner leads to the use of new WhatsApp
On the side, WhatsApp clearly states that communication with companies is completely optional. Users have control over whether they want to contact companies through WhatsApp. You can block contacts at any time and remove them from your list. Chats with companies are also clearly marked, so as not to confuse them with normal chat.
WhatsApp also tries to confirm that chats between users are still end-to-end encrypted. Therefore neither WhatsApp nor Facebook will have access to the content of the messages.