Is right to privacy while using Facebook services a fundamental right? Well, given some of the services they own - maybe they should be. WhatsApp is massive in the EU, while Instagram seems to be the replacement for Twitter for a lot of people now that Twitter itself is flooded with fools that nobody likes to interact with. We've already had Facebook suprise drop a "EULA change" on WhatsApp users that let them use WA data in the Facebook algorithms. The specific field Facebook is even in makes it unusually hard to leave. It's somewhat socially acceptable to not have a Facebook account. Its less acceptable to not have an Instagram and I don't think you can function in west-european society without WhatsApp at the moment; basically everyone expects you to have it.
So yes, privacy when using Facebook is extremely important (GDPR literally exists to codify privacy as a right) and pay-or-okay is holding it hostage.