Different people have different hip hinge angles depending on their genetics/morphology. So some people can have a lot more upright back angle while some will almost look horizontal at start. So long as the spinal erector muscles are rigid, and there is minimal flexion of the spine during the lift, then the lifting force itself will be predominantly coming from the hamstrings not the spinal muscles. The back muscles will be worked, but working to remain rigid and not to move the weight itself.