WhatsApp users joining rival platforms

The confusion with end to end encryption privacy is what gets me here. They had all that information before anyway, but I want to know if they're going to start being able to read my messages. I've recently downloaded telegram, and from what I understand this new data privacy change is just for better integration across facebooks apps, however it's not a change I'm particularly comfortable with as I use whatsapp because of its security and sense of privacy and also seeing other companies like apple speak out against this move leaves me slightly concerned for it.