The final lease value is a projection.
Determining the fair market-value at some projected point in the future can be very difficult to do accurately. Companies that lease cars hire mathematicians to provide the most accurate answers, but there are reasons they might want that number to be higher, or lower.
A higher final value can be good for everyone – consumers pay less during the lease, the dealership gets to control the price again when the lease is over, and the brand gets to highlight the retained value in their products while driving up the prices of used goods – which also support even-higher rates for new goods.
A lower number is great for the dealerships because the user overpays during the lease. Undervaluing the car is bad for the buyer who pays too much, and the brand because it shows their product does not hold its value.
As you can see, the determination of final-value is full of uncertainty and differing motivations. More than ever, beware the salesman here.