The reason why you're getting an error for the email field is that Stripe does not recognize linked records fields. As a simple workaround, you would need to add a new field in Airtable to lookup the linked records field "Email" and use it instead. Both fields will look similar, but the difference is that the API interprets them differently (lookup field is just plain text unliked the linked field which is an array of string IDs).
Unknown error code: email_invalid.
Updated over a week ago