This is actually a newer development intended to improve pedestrian safety by allowing to pedestrians to establish themselves in the crosswalk before traffic is allowed to move. It has been proven to decrease pedestrian accidents. [source](https://highways.dot.gov/safety/proven-safety-countermeasures/leading-pedestrian-interval#:~:text=A%20leading%20pedestrian%20interval%20(LPI,to%20turn%20right%20or%20left.)