Thanks a lot for your answer... ... but what if what we sell 'bills' or 'diamonds' through IAP and we want the player to purchase loot boxes with those without going through the In App Purchase? Should we ALWAYS use IAP for EVERY purchase to control whatever the user is able to acquire ? Again, thanks for your help.

I'm having an issue on fetching the leaderboards, have you been able to load them? here's my issue: https://developer.apple.com/forums/thread/713093

This is simply not true, not authenticated users cannot even access the public database even if it has records with world access