I'm not seeing your back rounding in the pull of either set. What you could have is more back squeeze, though. I would start by fixing your setup and gaze. You are throwing your legs back (extending your knees) between every rep. This is a waste of energy and almost always causes form creep over the course of the set. Indeed, for many reps you have the bar in front of mid foot a touch or knock the bar forward as you pull. So, get your setup dialed in, pull, and lower the bar back to that setup spot after each rep. Don't move your legs again. Just rebreathe and squeeze. Also, try to not crane your head/neck up as you squeeze and pull. Keep your neck neutral with eyes locked on a spot on the ground about 8' in front of you.