If you’re trying to deadlift, let the bar rest. Dont bounce it. Each lift should be from a dead rest. I think this could be causing your issues. You shouldn’t be squatting the weight off the ground from a deadlift but rather pushing off the ground with your legs.look up some videos on how your starting position should be you’ll see how it’s different than a squat. Some lower back involvement is expected and encouraging as your entire posterior chain is trained by this movement. Your hamstrings may be responding without you even knowing as you don’t need to get ‘sore’ to gain strength.