I read the handler and the last 20 failures in the events table. Every failing payload is a refund on a charge that was created outside a PaymentIntent, so payment_intent is null. The 3.4 refactor stopped guarding it:

const intent = event.data.object.payment_intentconst order = await orders.byIntent(intent)

Line 2 calls orders.byIntent(null), which throws before the handler ever reaches its retry wrapper. The 21 refunds that succeeded in the same window were all on PaymentIntent charges.

Guard the lookup and fall back to the charge id, which is always present on a refund event:

const intent = event.data.object.payment_intentconst order = intent  ? await orders.byIntent(intent)  : await orders.byCharge(event.data.object.id)

That clears 39 of the 41 on replay. The other two are past Stripe's 3 day retry window, so they need a manual resend from the Dashboard.