Pause deadlifts. I’d pause just right below the knee. Normally with pause deadlifts I recommend folks do it just off the floor, but in your case it’s the transition once the bar passes the knees.
You’re a little in the balls of your feet, so the knees slightly rebend, when you push back into your heels to correct it. When you try to transition back into your heels, that’s the when bar stops (slightly dips). It’s more of a ramping than dip. The pause deadlifts can help insure that you’re in the correct position before passing the knees.
Couple other quick things that might help. Leave the arms long before pulling. A quick little yank on the arms and your lats get loose. Flexed triceps and pull them into your lats. “Close off” the arm pits is a cue I’ll use sometimes to help think about tightening the lats prior to pulling.