Now I'm far from a deadlift expert, but I think you might be squatting a little too much at the start of your lift. Your hips seem to rise on every rep before you're able to pull, so maybe consider setting up from that position and avoid the unnecessary movement at the beginning?
Have to agree here. It's almost looks like a reverse squat. However, I'll wait for form master Noema to chime in.
On the bright side the weight shot up extremely fast, indicating to me, you have a ton of strength left.
Why is a seated barbell shoulder press so much easier than a standing press? I did 40kg x 10 x 3 without much issue. I would not get this rep range if I was standing.
It's making it easier because you don't have to use as much effort to keep yourself stabilized.