While we're not usually fans of "cash back" discount schemes as stand-ins for real sales, when making a big ticket purchase, they can be huge motivators to get products off shelves. Today is definitely such an occasion, with TCL's well-reviewed and range-topping R617 55" 4K HDR TV available for effectively $450 after rewards are taken into account when you using a qualifying Amazon credit card to make your purchase.
The TV is already on sale for its lowest price on Amazon ever ($530), but Amazon is offering an additional 10% in rewards cash back (on top of the standard 5% for the Prime Visa) on this specific model, meaning once those rewards points hit your account, you'll get back nearly $80 in Amazon Rewards. While points aren't real money, Amazon points are about as close as you can get to them - you can even use them to buy yourself an Amazon Prime gift subscription to underwrite the cost of your next membership renewal. So, they really are as close to real money as you can get. And without a doubt, you're probably spending $80 on Amazon in the next couple of years regardless, so we consider this a real versus imagined savings.
As for what makes the R617 such a bargain in general, this price almost certainly makes it the cheapest 55" TV on the market with full-aray backlighting and proper wide color gamut support. That makes it a good true HDR TV, as it will have substantially better black levels and can actually display much of the enhanced color range in the major HDR specs, versus merely supporting output for them. If you're looking for a modern, high-performance TV on a budget, you're probably not going to see another deal like this one for a while - I'm even tempted to pull the trigger myself.