Bug reports are generally best to go to https://github.com/python/cpython.
You should be able to define this yourself when building (hopefully your build backend allows for preprocessor variables). The multiple pyconfig.h problem is why we skipped an alpha, and this is the workaround, which will probably last until the day when the variable becomes redundant.
It looks like you’re using setuptools. They can start detecting the variable and passing it themselves whenever they like. Unlike the change to having multiple pyconfig.h files, we didn’t feel the need to block releases until they caught up. It’s easy enough to set the variable yourself.
That’s a bug, if you’ve selected the option for the freethreaded binaries. It should include the right libs.