Please clip your videos at the start more.
Get your chest up more at the set up. You may need to think about dropping your belly below your thighs without moving your shoulders or butt.
Less important stuff:
You're hanging out too long. After the first rep, take a big breath, set your chest and pull. Put it down. Big breath. Set your chest. Pull. Repeat. Sitting in the bottom this long is going to make it a lot harder to finish.
Set the bar down faster. You have bumper plates. You should basically be dropping the bar, but without letting go of the bar. That's how fast it can be.