With macOS 11 and in particular Arm64 the binary installers for macOS switched from building with an old version of Xcode to using the latest versions. This was required for arm64 support, with a side benefit of using a better version of clang with proper PGO/LTO support. The build still uses macOS 10.9 as the deployment target, which means the change doesn’t affect which older systems are supported by the installer for macOS on python.org.
One thing to consider is that the release notes for the current Xcode 14 beta (with macOS 13 support) mention that this version of Xcode only supports building for deployment on macOS 10.13 or later. This means we won’t be able to use Xcode 14 to target macOS 10.9 as we do now.
I haven’t checked yet if this affects functionality, that is if macOS 13 introduces now system APIs that are already supported in posixmodule (or should be supported there).