Payment
If a customer’s subscription order renewal payment fails, then Stripe will retry capturing the payment several times (according to your Stripe settings).
Emails
CartGenie will send the Payment Failed email to your customer letting them know.
Orders
A renewal order is created only on a successful payment; failed payments do not create anything. The renewal order will only be created once the payment actually succeeds. So there are no separate unpaid orders created for each failed attempt.