Maybe it's just a coincidence, but the very first item I've sold and
shipped to a FF the buyer came back over a month later and opened a INR
case. Even with USPS showing it delivered over a month prior. They are
also very rude and called me a fraud. ...
Could it be an item that eBay is deluged with sellers? Check price
against other listings. Also check all your listing details and category
for accuracy.