I'm not really sure I'd call this fraud. In that Opendoor delivered the product the customer was promised and paid for. Lying about the quality of that product compared to the alternatives is dishonest for sure but I don't think anyone here was really cheated. It's understood that when companies tout their product compared to competitors it's not a fair comparison.
It's not even clear to me that they lied. If someone claims the "true market value" of an asset is $X, and the owner accepts an offer of $X, then the market value of the asset is indeed $X, no?
A market cannot just be two people. If I sell you a brand new Rolex for $1, I would say I’m selling it to you at a discount from the market rate, because if I posted it on an open auction like eBay, I’d receive higher bids than $1.