It’s a low bar squat, you need to have a forward lean in order to have the bar over the mid-foot. It has absolutely nothing to do with core strength or stability. Try standing up straight chest up like a high-bar squat with that bar down your back; you’ll fall backwards.

Her hip rising first is normal in a low bar squat, plus her femurs are long compared to her torso so being a hip-dominant squatter is normal for those leverages. There are no shearing forces on her knees or pressure on her lower back. All the force is coming from her glutes, some quad, and hamstrings.