By default, the iOS application loads the Facebook SDK on startup of the app. When I check the monitoring of my local DNS resolver, I can see that Spotify makes a request to "graph.facebook.com" on startup, without even clicking on Facebook integration or using "login with Facebook".
This behaviour caused the crashing app yesterday, because the app couldn't contact the Facebook SDK on startup. This makes the iOS app less reliable, because a faulty Facebook SDK causes the entire app to crash. The second point is that this SDK makes Spotify send data about every user to Facebook, even when they don't have Facebook and don't use any Facebook functionality like "login with Facebook".
In my opinion, the iOS app should get the same behaviour as the Android app. That means it only loads the Facebook SDK, when using Facebook functionality. This will make the iOS app more reliable and more privacy friendly.