The spike traces back to a stricter idempotency check shipped in 14.0. Retries now collide on a key that was previously regenerated, so the queue rejects them as duplicates and re-enqueues:

• Burst correlates with the 12:02 UTC rollout window.
• Affected path is limited to checkout-api.
• No data loss — payments are deferred, not dropped.

Scope the idempotency key to order_id + attempt instead of order_id alone. That preserves dedupe within an attempt while letting genuine retries through. I can open a PR against checkout-api with a test.