WhatsApp has already had multimillion euro fines for their privacy practices. Just because it has E2E encryption does not mean it doesn’t sell other data. A company whose business model is to sell your data is going to sell your privacy along with it.

Being open source is nice, but not required for privacy.

https://www.cnbc.com/2021/09/02/whatsapp-has-been-fined-267-...