After an apple subscription has expired, the iOS user can go to subscriptions and resubscribe there in the OS without going into the application directly. This usually takes a few seconds to complete, since immediately after resubscribe when going into the application the customerInfo() still does not show any active entitlement until after about ~30s.
During those 30s the application will show a subscribe screen. What happens if the user tries to make another purchase in the app during those 30s (either same product or a different one)? Will they get double charged and how would the developer know?
I am not sure if this is the same situation on Android yet.