They’re a part of the rapidly expanding world of so-called less lethal weapons, named such as they are because they are ostensibly less likely to send you to the ancestors when used against you. These weapons come in many different varieties, ranging from “smaller” 9 mm rounds designed to be fired at a person’s legs or torso, to the much bigger, pop-can-sized 40 mm rounds that are designed to be “skip fired” by ricocheting off pavement or other hard surfaces towards their target (police historically do not do this, and simply fire at the target).
I do not for one second buy that they were "designed" to be bounced off the ground. It's an idiotic concept from the get-go: it's hard enough to aim a conventional firearm. Expecting any kind of accuracy from a ricochet fired by an untrained and easily frightened moron is a fever dream. Fucking no one expected rubber bullets to be bounced into people's legs; it was always an excuse for pigs to shoot into crowds. The casualties are a feature, not a bug.
Unconfirmed btw