Remove Entitlement from Google play console

[wicaodian]

I have a single product purchase in my app, the purchase process went smoothly, and restore is also working automatically.
But when I tried to refund the purchase to the customer and check the box to remove the entitlement it didn't trigger OnProductPurchased.

Since there is no owned product it's not triggering anything and the customer ends up with a full refund and full entitlement of the product.

How do we handle this thing?