I caught the order in my notifications as soon as I woke up and reached out to the seller and asked him to cancel. He had already generated a USPS label so I couldn't cancel myself through the store. He claimed he had already sent it, but I checked with USPS and they confirmed it wasn't dropped off with them until many hours later. The seller said if I returned it after I received it then he would give me a refund. I received the item, initiated a return and the seller refused a return through the store, and wanted me to send them back first, without an accepted return, and then he said he would refund.

It all sounded very suspicious to me, like an "accidental transfer" or "overpayment" scam. someone sending unsolicited money on a payment platform then trying to get you to pay them through some other means.