If you would’ve read comments in this post thorough, you would’ve found it most likely has to do with the payment providers and not apple itself, as there’s nothing apple can do in that case (other than pay the difference from their own pocket, but they have no legal requirement to do that). Thus it’s not random.
Apple reserves the right to keep its commission and doesn't attach it to payment processing issues. It can do whatever it wants, and we can only guess.
