Ensure to have always an idempotency key
Currently, we use the stripe_checkout_id as idempotency key but it is not always filled if the payment does not follow a checkout process. Also the checkout id is used as an authentication method for the checkout process, so it is better to not share it even with Stripe.
I propose to have a specific field that is filled with UUID4 by default and to use only this one as idempotency key.