I just noticed the new docs have:
If you are not using RevenueCat's anonymous IDs as described above, and are instead providing your own app user ID on configuration, do not call configure in application:didFinishLaunchingWithOptions:. Instead, call the configure method in your root view controller's initialization method.
This is a fairly major change, since my app has a complex init sequence. It would be helpful to know more about what's going on here, so that I can correctly adjust my init sequence.
I have read about the unavailability of the KeyChain during prewarming, but what exactly is requiring this change?