The stars and numerals look "fatty" a usual sign of a counterfeit; BUT the photos are not sharp. Did you see if it is a match at PCGS?
Cert appears to match but the label lettering seems off to me which admittedly could just be from the picture
The eBay listing says it is a proof-like strike type, which it is not. Something off about the labeling, at least in my eye. And the PCGS price is over $1600, which makes the opening bid a bit low, at least for me. If it ain't gelling in your mind, it ain't gelatine. And it's not gelling in my mind.
It matches, but the most glaring thing is the reverse. It's a '79 reverse and the mintmark is all wrong.
This is just my personal rule: with one very notable exception, I don't buy coins from eBay dealers whose main business is not selling coins. This seller seems to be primarily an antiques dealer. Somebody can stick sellers like this with a bad coin and they don't know the difference.
Both the slab lettering and the coin seem off. I can't put my finger on why, but after looking at a lot of genuine coins, the questionable ones just stand out...
Not commenting on the coin, but I was scanning Heritage's Sunday auction and I saw a slab typeface just like this one on another coin.
Lousy pic but still wing tips about in rim. CC is wrong. Some letter placement wrong etc. My humble opinion is counterfeit.