After pushing the iOS 13 Golden Master version to developers, Apple has also placed new demands on app developers, by April 2020, all newly submitted apps (including updates) must support the iOS 13 SDK. In addition, Apple mentioned in the developer portal that applications that want to enter the App Store after this must provide better “all-screen” support for iPhone XS Max and subsequent models. As for why the iPhone XS / XR is not included, it is currently unknown.
Apple is committed to providing users with a consistent, state-of-the-art experience, so the new policy mandated in April 2020 is understandable.
In iOS 13, Apple introduced many highly anticipated improvements, such as global dark mode improvements and the Sign in with Apple single sign-in tool. Compared to iOS 12, this year’s change will be quite large. For developers, iOS 13 also introduces a range of programming support, including ARKit 3, Core ML 3, and major improvements to the Siri Assistant. In addition, developers were asked to use today’s newly released Xcode 11 GM and to test on devices running the latest version of iOS GM before submitting the software to the App Store for review.
Source: Apple Insider