Hold the ball, drop it low, build legs anywhere.
Keep the ball close to your chest. Letting it drift out front pulls you forward.
Holding the ball at your chest works like a goblet, the front load lets you stay upright and sit deeper, so your quads move through a bigger range of knee bend. Your glutes take over at the bottom to drive the hips back up to lockout. It is a squat you can do anywhere with one piece of kit, which makes it perfect for learning depth and for keeping legs honest away from the rack.
At least until your thighs are parallel to the floor, deeper if your heels stay down and your back stays neutral. The chest-held ball actually makes depth easier because it counterbalances you.
Same idea, different implement. The ball is easier to hug close to your chest, while a dumbbell or kettlebell goblet lets you go heavier once bodyweight plus ball feels light.
The ball has probably drifted away from your chest, which drags your torso with it. Pin it against your sternum, brace, and think about sitting between your heels instead of reaching forward.
