App subscription behaviour + upgrade/downgrade after app reinstall

I’ve encountered a similar situation regarding app subscription behavior after reinstallation. Specifically, when a merchant:

  1. Subscribes to a discounted annual plan.
  2. Later uninstalls the app, canceling the subscription.
  3. Reinstalls the app and selects a monthly plan.
  4. Shopify then issues a prorated refund for the unused portion of the annual plan and activates the monthly plan immediately.

This sequence seems to bypass the intended behavior of APPLY_ON_NEXT_BILLING_CYCLE, which typically maintains the current plan until the billing cycle ends during direct plan changes.

I previously raised this concern in another thread:

Has anyone found a way to handle this scenario effectively within Shopify’s billing framework?