It is absolutely true that WhatsApp collects your contacts' phone numbers and your social graph. Unless WhatsApp has stopped doing that, in which case it should make a big announcement.
I don't know if the social graph is used outside WhatsApp, so that part may not be true, but it is within the privacy policy to do so (at least the one I see, EU may have a different one), the privacy policy says WhatsApp may share information with Meta to among other things:
> improving their services and your experiences using them, such as making suggestions for you (for example, of friends or group connections, or of interesting content), personalizing features and content, helping you complete purchases and transactions, and showing relevant offers and ads across the Meta Company Products;
And there have been waves of policy updates, notifications etc specifically to get these terms. That doesn't mean Find my Friends gets this information, but I thought there was at least discussion of it.