I saw my dog doing this and I was going to ask that question here but I looked it up instead. I thought I would share the answer for anyone else who was curious. It seemed they they were trying to bury their waste, but no, that’s not the answer at all.
"This dog behavior is a way to mark their territory. … When a dog kicks the ground after defecating, they are releasing pheromones onto the ground . In addition to the scents from feces and urine, these pheromones relay territorial claims, sexual availability, possible food trails and warnings of danger. "