The electronic gift cards were bought in 2021 on Newegg.com.

I confirmed with Delta that both of the gift cards were redeemed for a flight (or flights) on July 15. Now they're saying that the cards were for a flight on November 12 (not November 13 as originally stated) and returning 21 January. This is good news because it sounds like there's still a valid booking that's a few months away, so there's an easy way for Delta to investigate, cancel the booking(s) and return the money to me, although they are currently refusing to do so.

My plan is to file a police report, follow that up with an FTC complaint and DOT complaint, then a state attorney general complaint. I'm now very confident that I will get my money back. I suspect we're going to find that the flight(s) were booked to a high-fraud country, but who knows?