Amazon refunded order. No return. Insight appreciated

I sold to a business customer a book that I bought on eBay. I ended up losing money on the book. I originally bought the boook hoping to flip a profit from eBay to Amazon but it didn’t work. I never initiated the refund and don’t see any return. The customer just said QR code doesn’t pass authentication. My gut feeling is telling me I bought a fake book on eBay to sell on Amazon and the automatic refund was amazon fraud department/inspection? Any insight appreciated