This can happen when a customer's bank approves the charge despite the CVC or ZIP code mismatch.
You can use Radar's built-in rule to block charges that fail the CVC or ZIP code (AVS) check.
Without a specific block rule in place, a charge can still be approved by the customer’s bank, even if the CVC or ZIP code (AVS) check fails. Banks take a variety of signals into account in their own systems and may see a charge as being legitimate despite the check not passing, and then send the charge approval along to Stripe.
If you were looking for more info on charge declines, you can read more about declines in our Docs!