Personally, I found this article super useful. We've had long discussions at my company about what Facebook's announcement about not supporting IDFA opt-in means: https://twitter.com/rjonesy/status/1298662658934222848
This article made it much more clear. It's one of the only ones that addressed why Facebook says advertisers have to create a separate advertising account for iOS 14 ads, for example.
What Facebook tells you: " To help preserve the fidelity of app install campaign measurement, we will require the creation and usage of a dedicated iOS 14 ad account "
What the article explains: " Unfortunately, however, it will require them to set up a completely new advertising account to run campaigns for iOS users, because it’s not going to apply Apple’s new privacy protection measures any further than it has to "
Makes sense. Facebook's recommendation to apps showing ads is to implement Facebook login or uploading hashed user information (Advanced Matching). Apple is already cracking down on those approaches, like saying any app that has social login must also support Apple login.