I don’t feel great about this ruling. Whatever a “reasonable” fee is supposed to mean, Apple will interpret it to some ridiculous amount. Before the ban, they tried to charge 27%
I think Apple will have a very hard time arguing that the "reasonable" amount is a percentage of revenue with no cap.
It should be based on the app size, so maybe developers will stop shipping apps with a single feature and one button that takes 700 MB because of random bloated third-party SDKs that aren't even used.