After receive the call, usually the status will be "created", and sometimes will "refunded" due to the simultaneous execution.
Please treat both as successful refund.For "refund_failed" status, PayPay will conduct batch process for refund payment, for unsuccessful refund, we will keep retry until success refund, therefore the final status should be "refunded".
ウェブペイメント webpayment キャンセル cancel 返金 refund Refund a Payment status ステータス