Generally speaking, you leave your feet and knock someone down, it’s a personal foul. There’s obviously exceptions but that’s what I’ve seen, particularly when you’re being defensive. Also, hand in the back that results in a player on the ground will also be called a foul. Just judging from that last panel, she pushed her down and it’s a foul. It’s also just playing dirty during a free game. You don’t risk player injuries like that during a F*ckin pickup game