Critical Issue: APPLY_ON_NEXT_BILLING_CYCLE Causing Significant Revenue Loss

[abueler]

After more testing I found out what exactly the problem is and how to reproduce it. It’s described in this newer ticket:

Loophole in Shopify Billing API: Merchants Exploiting Annual Subscription Discounts

I’m facing an issue with our app’s annual subscription model that’s causing revenue loss through what appears to be a Shopify billing system loophole. The issue: Merchant subscribes to our annual plan (with a 30% discount) Later, they uninstall the app (canceling current subscription) Merchant reinstalls the app and selects a cheaper monthly plan Shopify immediately issues a prorated refund for the unused portion of the annual plan This differs from normal plan changes where APPLY_ON_NEXT_BI…