The flag
payments.fallback_provider: when on, payments sends charges to the fallback card provider instead of the primary.
Costs
The fallback charges a higher fee per transaction, so it is for incidents, not for everyday use. Switch back when the primary has been operational for 30 minutes.
How
Turn the flag on through the flag action, with the incident in the reason. Expect checkout p95 to fall within two to three minutes as the latency window rolls over. Turning it off is the inverse action.