Most developers treat a successful authorization as proof the money moved. It didn't.
Auth is a promise from the issuing bank. Settlement is when you actually get paid. The gap between them can be 1 to 5 business days depending on your acquirer, the card network, and whether your processor batches or real time streams.
Build fulfillment on auth, and you'll occasionally fulfill orders for transactions that settle short, get reversed, or fail after capture.
The auth success rate and the settlement success rate for the same batch are almost never the same number. Disputes, network reversals, and processor clawbacks all happen after the auth. Your revenue numbers are wrong until you reconcile against actual settlement files.
Bonus gotcha: if you're doing preauth captures for hotel or rental use cases, your capture window is usually 7 days max before the auth expires on the network. Most teams find out when captures start failing silently.
What does your settlement reconciliation actually look like?