Saw someone squat 200kg for a double today, pretty impressive especially for my gym. The average is a 1/8th ROM with 70kg. Realised half my problem is my glutes dont activate during squats. In the start position, my back has an arch but its kind of not tight enough, my abs are tight but its almsot like my ass just sticks up behind me. I can squeeze it down and in, which gives a much more stable/powerful position, but i lose this tightness as soon as i descend. Hard to describe, but im pretty sure the glutes should be active and tight all the way down and not just kinda popping out loosely behind your body.