intent_client_secret, you need to confirm the payment using the Stripe SDK
payment.requires_auth, every time the subscription charge needs to be re-authenticated. You will need to handle the flow to ensure that your customer's card is re-authenticated. This could be handled by sending an email or a push notification to your customer notifying them on that a payment needs to be re-authenticated. Have a look at our SCA confirm payment page example to get a better understanding of the flow required to re-authenticate a payment (or just clone and copy our example!).
POST /payments/<payment_id>/confirmwith the
payment_client_secretproperties in the body.