Just watched your pulls, getting closer to 500, so I know this will be a big bitch to hear, but you really need to slow it down, and work your form with 385-415 for lots of sets of triples, and you’ve gotta make them perfect. I know it sounds light, but try this workout.
try this for a few weeks:
week 1
day 1
deficit deadlift 60%x3x2 sets
deadlift 70x3x2, 80x3x2, 85x2x4 sets
split squats weighted 3x10
abs
day2
deadlift up to knees 70x3x2
deadlift off boxes, knee height 90%x3x2, 100x2x3
week 2
deadlift 70x3x2, 80x2x6 sets
walking lunges
abs
day 2
deadlift up to knees 70x4x4
deadlift from boxes 95x3x4 sets
week 3
deadlift up to knees 75x2x5 sets
deadlift from boxes 85%x4x4
day 2
deadlift off boxes 80x3x5
sntach grip box pull, slow eccentric 65%x4x4
week 4
deadlift 80x3x3, 85x2x3
day 2
deadlift to knee 70x3x2, 75x2x4
deadlift off box 85x2x3, 95x1x3 sets
Do that for a month, then see how your form looks, it really uilds a deadlift