Comment by ryandrake

I think a lot of people in this thread are mistaking SDK version and minimum supported version.

The App store requires you to link with a minimum SDK version, but the minimum supported version is set independently by the developer in Xcode. The latest version of Xcode + the latest SDK can still support devices running iOS 15. Developers are deliberately choosing to drop such support. Or maybe they just don't know how, as evidenced in this thread.