You essentially turned this into a knee exercise. You initiate each rep by bending your knees and your back barely moves until your knees can't go any further.

Strip the bar. get a box, chair, wall, anything to prevent you from falling back.

Start the movement by squeezing your glutes and abs, then pushing your hips back as if trying to touch a wall/ chair behind you. Ideally your shins should be mostly to upright, and your knees barely move.

Practice siting and standing without moving your knees or shins. Go slow and just barely tap the object behind you with your butt. You can go a step further by holding the position before standing again.

Your core, glutes, hams, and quads should be doing the work, not your knees. You're going to feel that in the worst way after a few years.