@mlekar @zuck I should have clarified! Meta is probably reading the meta data (location, local numbers, frequency, names associated with phone number, etcetera) & is sending that to their advertising department.
They probably (hopefully) can not read your messages.
This is an old Reddit article where people debate how secure WhatsApp is: https://www.reddit.com/r/whatsapp/comments/k5zjol/can_whatsapp_read_endtoend_encrypted_messages/
Ultimately it comes down to trust.