We’ve detected that this app is using an old version of Google Play Billing. By November 1, 2021, all app updates must use Billing Library version 3 or newer. Update to Billing Library 3 before this date
Change the version of ‘com.android.billingclient: billing’ in proj.android/app/build.gradle to 3.0.x.
Test the purchase on a real device and make sure it works fine.