So, I did a search, didn't find anything about this.
Back in December, Apple changed it's rules for app store apps, requiring them to disclose the rates for virtual items.
For reference, under 3.1.1 (In-App purchases)
Apps offering “loot boxes” or other mechanisms that provide randomized virtual items for purchase must disclose the odds of receiving each type of item to customers prior to purchase.
Has anyone seen any sort of official rates posted? If not, wouldn't this put them in violation of Apple's developer ToS?