> Uncommonly downloaded is applied to any download that is new or has been modified/updated until Google has a chance to examine the download using multiple data centers. Once the download has been examined enough times, the warning will be removed.

So apparently we just have to wait until Google's servers decide my app isn't dangerous. Ironic considering I paid the $100 for Apple to notarize the app through Developer ID to remove that same warning from macOS when you first launch the app!