OpenSea's head of product was apparently using burner wallets to purchase NFTs, then featured them on the front page of OpenSea to hype them up and sell them for a quick profit.
He made the mistake of returning the profits to his personal wallet which was publicly known (since he had his cryptopunk in there), which is how he was caught.
Here you can see one transaction where he returns the profits to his main address. He got the profits by flipping the NFT that is featured on the front page at this moment.
If you check the transaction history of the NFT that's currently featured on the front page you can see him (7942F4) buying it for 0.25 ETH yesterday, and selling it for 1.5 ETH a few hours later after featuring it on the front page.
And this was just one transaction. He has been doing this for a while now.
Some twitter users compiled a list with which NFTs he sold, for how much he bought them, and how much he sold them. You can find them here
edit: He made 19 ETH in total according to this