Why don’t you read the warning there? Comments are written by the marketplace users. Gameflip will never write comments on listings.
Unfortunately you’ve been scammed. There’s nothing that can be done since you already delivered the item and didn’t read the caution. That was a mistake from yourself
You were scammed by a person who wrote comment on your listing, sadly gameflip can’t help you with this. You will not receive your money back as it never was sold so protection doesnt work here.
You never sold item, someone wrote comment on your listing and you just send item to the person who wrote the comment.