If you tried to intercept requests from the Facebook app on iOS using a proxy, you will be hitting by their message alert The operation couldn’t be completed. That’s because of their SSL Certificate Pinning protection which must be bypassed to be able to intercept requests and responses from their server. In this blog, We will go through their iOS app trying to bypass their SSL Pinning.

And the same for instagram: https://www.cyclon3.com/bypass-instagram-ssl-certificate-pinning-for-ios

source: R