Another reason that I see this as unlikely to apply to Gems:
China actually has a similar law on the books, where all games must disclose odds of getting things. However, their law says:
“Online game operators should promptly display the name, performance, content, quantity, extraction or synthesis probability of all virtual props and value-added services that may be extracted or synthesized on the official website of the game or randomly selected pages.”
…or in other words, you must display the odds of anything that’s MTX-based but also everything else too even if it’s just a normal part of free gameplay.
Look at Apple’s very, very specific wording in comparison:
“that provide randomized virtual items for purchase”
I mean, this is obviously all speculation so who knows…but it just feels really unlikely to me.