There are two primary factors that can cause your apps to be invisible to users on the Google Play Store.

1. If your users are located in a country different from the one where the app was originally released, they may not be able to find it in the app store. This limitation arises from the fact that apps are made available in specific countries according to licensing rules and regulations. Users whose Google Play account settings are associated with a different country might not have visibility of your app.
   
2. If the user’s phone fails to meet the minimum requirements of the app, specifically Android 9.0, it will not be displayed in their search results. The app’s compatibility is contingent upon a certain Android version, and if the user’s device falls below the required threshold, the app will not be visible to them.