YSK that Amazon has different prices for different people
My girl was looking for a dress for Halloween. Yesterday she found one on Amazon for € 35 and put it in the cart, but did not buy it. Today she looked it up again and it was € 50 so she asked me to look it up with my phone with my Amazon account - it turned out to be € 23 for me, less than half of what it’s for her!
It's often a checkbox in green near the checkout button if the item and can be the most absurd percentages that shift daily and are often better discounts than sale days.
Add something to your cart, you won’t see the coupon u till you’ve added it. It will have a button to “clip” the coupon thus applying the potential savings.