WhatsApp is enforcing a new controversy privacy policy that, as far as I understand, shares data from your chat messages with Facebook to provide you with "tailored ads" on Facebook.

How can WhatsApp share this information with Facebook, if the messages are encrypted end-to-end?

Does it mean that the messages are encrypted in my phone, sent encrypted (with the key to decrypt) to Facebook for targeting Ads, and another message is sent with the key to decrypt to the cellphone of the person I'm having a chat with?