After the user logs in to PayPay via the PayPay app or PayPay website, PayPay will redirect them to the merchant's site with a one_time_token appended to the redirectUrl configured in pp.getLoginUrl, pp.render, or /v2/smartpayment/qr/sessions.
Example:
redirectUrl : https://paypay.ne.jp/smartpayment.html
Redirected URL from PayPay: https://paypay.ne.jp/smartpayment.html?one_time_token={value}
There is no issue if the user is redirected to the merchant's website via a browser or if the redirectUrl with the appended one_time_token is opened directly as the URL in the Webview. However, if the URL is modified by the merchant and the one_time_token is not properly passed to the Webview, the subsequent pp.init will fail. Therefore, make sure to always open the Webview with the one_time_token correctly passed.