I would think the price changes happen overnight. With their system each RFID type price label can be flipped when the push the pricing to the register system.
I’m sure the old way was a deterrwnt in changeing prices because they had to call staff in to swap labels. Now it is computerized, so on a whim they can adjust.
We had an oat drink we liked one day 4.99 go back to grab another the next day 7.99. Few days later 3.50…we said screw this company and just got it at Walmart where price was consitent every time.