Fake Buyer to Force a Delisting
This is really a scam by one seller against another. They get someone to buy an item that doesn’t have the “must pay immediately” box set. The listing is pulled from the marketplace, but they never pay.
The buyer is just trying to eliminate the competition.
This happens sometimes, when your item is priced significantly lower than the others.
The fix is to cancel the sale, but Ebay may ding you for this. There’s also a process to cancel for nonpayment that won’t ding you, but it’s complicated.
The Fake VERO Letter
Ebay’s VERO system is supposed to help prevent counterfeit or unauthorized sales of branded items. Some competitors will send a fake VERO letter telling you to quit selling one of your items.
Just be aware, and ignore the letter if it doesn’t look real.
The Real VERO Letter from a Lying Competitor
The competitor might be able to register as the owner of a trademark. Then, they can complain to Ebay about trademark misuse, and Ebay will send you a VERO letter and possibly remove the listing.
There isn’t much you can do about this, especially if you do not have a regular supply of said product. Just be aware that this can happen.