The Android "Support Libraries" have been deprecated by Google in favor of the AndroidX libraries. Google will no longer be making updates to the Support Libraries (v28 is their last version). New features will be going to AndroidX instead.
The Titanium SDK and its modules needs to migrate to the AndroidX libraries. Titanium's app builds will also need to leverage Google's "jetifier" tool which replaces prebuilt Android libraries, replaces their references from the Support libraries to AndroidX by hacking the binary (this is a Google sanctioned feature) so that 3rd party modules will be backward compatible.
AndroidX is best implemented in the app "build.gradle" file via...