The update, spotted by Polygon, includes a change to the payment section of the guidelines, which now state:
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.
In practice, this should function the same as Blizzard’s new rules of disclosure for Chinese Overwatch players. The company recently listed the odds of getting each kind of item in a loot box on its Chinese website, after Chinese gaming regulations forced the transparency.
It doesn’t actually say in the rules where the disclosure must be. I checked the app page for Hearthstone (the first game with “loot boxes” on iOS to come to mind) and couldn’t find anything explicitly stating the odds.
This change doesn’t really effect the way loot boxes themselves function, but it might skirt some kind of gambling regulation if the company tells you ahead of time how likely you are to get the prize you want.