No real idea, but it might be that your eBay ID is anonymized just as it is when you leave FB for others.
You see your own ID, as does the seller, but the rest of the world sees only something like c***5 .
Look at any other seller's FB and you will see that the buyer's name is not public.
BTW- it's way too late now, but that neg you left last year could have been a refund under the Money Bay Guarantee.
It would be a money back, not a replacement, in part for the reason you outline in the neg.