I think the only way you can consider iOS “amateurish” is according to a ridiculously high standard for phone software that Apple itself is responsible for normalizing.
iOS 26 actually has a lot of great features and convergence with the rest of the ecosystem (e.g. preview is awesome). But it lacks the polish that Apple has a reputation for; unfortunately 50% worse polish for Apple is still significantly better than Android and Windows. There just aren’t greener pastures to move to.