According to https://android-developers.googleblog.com/2017/12/improving-app-security-and-performance.html:
In August 2019, Play store will require that new
https://github.com/facebook/react-native/issues/2814
Facebook seems to be dragging their feet on supporting 64 bit builds.
You can check the intermediates in the build folder to see what abis you are supporting.
https://developer.android.com/ndk/guides/abis.html
Android takes the lowest common denominator of build abi. This is going to become an issue if Facebook doesn't address it soon.