Twitter Blue costs $11 per month instead of $8 on iOS
twitter.com
twitter.com
But most of the time, if an app has a website you can purchase a subscription from there but cheaper.
This kind of price difference is pretty standard but when more consumers catch on to the fact you can pay less by via a different channel, I think more of them will do that. Cuts like 30% will eventually come back to bite Apple in the coming years as consumers become more savvy for a better deal.