When doing a "production" build, the x86 and x86_64 architectures should be excluded from the built Android app by default. That is, only ARM architectures should be included.
We have been excluding x86 from "production" builds since Titanium 7.0.0. We want to maintain this behavior in Titanium 9.0.0's gradle builds and exclude x86_64 as well. These architectures are mostly needed for testing purposes in the Android emulator. Removing these architectures can reduce the APK size by a significant amount. Also, physical Android device that support x86 are extremely rare.
Modules built with Titanium 8.x.x and older do not support the x86_64 architecture. Only modules built with Titanium 9.0.0 and higher support x86_64. When you include a module that does support x86_64 into a Titanium 9.0.0 or newer app, then the build system will strip out all x86_64 architectures from the app. It's all or nothing, otherwise a crash will occur on an x84_64 device/emulator. This means if you want your app to support x86_64, then all modules must be built with Titanium 9.0.0 or higher.
How to Override:
You can override this behavior and specify which architectures you want to include in the build by adding the following <abi/> entry in the "tiapp.xml" file.