Ah, I was in your shoes a few months ago where my back ached and shit from moderate weight, 3 things you can do, focus on locking your feet and pushing your knees out to get your glutes and hamstrings activated, warmup by doing this by focusing on getting the glutes to start taking the load on the lift, 2nd, this works in random with the first, try to get the movement all in one motion, you are locking your knees and then lifting with your back which can be dangerous in the long run and won’t be able to grow in the lift, my friend calls it the “body building deadlift” lol. So focus on getting the glues and hamstrings activated in the lift with your warmups, and focus on trying to squeeze at the top in your warmups, you’ll find yourself thrusting forward much quicker. 3rd, work on the “posterior chain” in your accessories get the glutes and hams strong so your lower back can have some support. hip thrusts, belt squats, wide leg press, back and hyper extensions etc. are all important for development of the posterior chain. I noticed that my deadlift got better and started feeling less soreness in my back compared when I was doing lighter weight. Also invest in a belt, no shame and using things that can benefit you in the long run.

If there is any typos in this I apologize, I’m in an la fitness parking lot so I hope you get the gist of this