In addition to local laws, app stores usually require disclosure:
Google:
Apps and games offering mechanisms to receive randomized virtual items from a purchase including, but not limited to, “loot boxes” must clearly disclose the odds of receiving those items in advance of, and in close and timely proximity to, that purchase.
Apple:
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.
Amazon:
Apps offering “loot boxes” or other mechanisms to receive randomized virtual items from a purchase must clearly disclose the odds of receiving each type of item to customers prior to purchase.
Same for Sony, Nintendo, Microsoft.