That's not anything like what's happening here though. Epic starting distributing apps on the iOS app store knowing full well what the conditions of doing that was. Apple hasn't changed anything regarding this. Epic have decided that they don't like the rules that they originally agreed to so they ignored them. And Apple followed the guidelines and fought back. As they should have. Epic don't have to distribute their apps on iOS, but if they do they need to follow the rules that other app developers have to follow.
I think 30% is quite steep. But that's not the point. If Epic didn't like the rules then they shouldn't have agreed to them.