They are selling something that doesn't even exist (in any legal form)
- "Photoshop 2021", but Photoshop is a subscription, costing $10 a month.
- Selling a perpetual license for the price of a few month's subscription - but this is an impossible bargain - there are NO perpetual licenses for Photoshop.
- Making it sound like "last year's product" so people think there's a reason for a clearance (Adobe never have clearance sales).
So, what would you get? Maybe nothing, maybe a modified version of Photoshop which infected you with a virus or worse; maybe follow up from Adobe if you are found to be using stolen serial numbers; and maybe your credit card details stolen.