refund_exceeds_captured
HTTP 422, type invalid_request_error.
The refund is larger than what is left to refund on this payment.
Why it happened
Refunds on one payment add up to the captured amount and no more. The message states what is still refundable, in minor units.
How to fix it
Refund an amount up to the remaining refundable amount.
Retrying: retry only after fixing amount, to no more than the amount still refundable. This refusal happens while the request is processed, after its Idempotency-Key is claimed, so send the corrected request with a new Idempotency-Key.