According to the "Implementation Plan for Exempting Small Passenger Cars from Toll on Major Holidays", no toll will be charged until the passenger cars leave the toll booth during the free time. It is judged according to the time when the car leaves the toll booth. If you leave the expressway during the free time, you don't need to pay, otherwise you will have to pay before the expressway is free in 2022.
Expressway toll collection is a way to recover the cost of expressway infrastructure by directly collecting vehicle tolls from expressway users to compensate the investment in expressway construction and maintenance.