I post here, don’t want to hijack the other log.
Legs lenght itself is not enough to explain a “not perfect” squat.
The ratio between the tibia and the femur + ankle mobility will dictate your squat.
Just look at Simeon Panda, really long legs, but huge tibia and an amazing ankle mobility
Edit : If you look how close his ass is from the floor and his femur is just under the parallèle. Try to squat this low and look at your femur position (and your torso)