Why did a client receive a reminder after paying?

Check whether the payment is actually received and linked to the invoice. A client's transfer confirmation, a payment being processed, and a settled credit are different records. Compare the amount, currency, invoice number, and payment reference before deciding that the reminder is wrong.

If the payment is linked to another invoice, is only partial, or was paid outside Skydo, tell support what happened and provide the evidence. Ask support to check the invoice balance and any further reminders. You can also tell the client that you are checking the record so they do not send a duplicate payment. Do not delete the invoice or mark it fully paid without confirming the receipt and remaining balance.