IOS asks for "Touch ID Login" after successful app purchase - why?

I currently have an app in Testflight that implements an in-app repeat purchase.

I am using react-native-inapp-utils to implement it. The application calls the function InAppUtils.loadProducts()

and then in the success callback of this InAppUtils.purchaseProduct()

.

This all seems to work, but the dialogs that iOS presents during the purchase process are weird.

First, the iTunes login prompt is displayed by TWICE. This appears to be "normal" in Sandbox accounts.

But what I don't understand is the Touch ID prompt that appears after a successful transaction. I have a Touch ID, but why did I ask to "enable" this after purchase?