Quick answer: Face-on: at the top the weight is on the lead foot and the spine tilts toward the target; on the downswing the weight falls backwards.
What it does to the ball
The weight sequence runs backwards: weak, high shots, thins and a slice; compressing the ball becomes impossible.
Root causes (by frequency)
Keeping the head exaggeratedly still
A flawed concept of turning: tilting the spine instead of rotating
Poor trail-side stability
How to fix it
At the top, feel the pressure in the inside heel of the trail foot with your chest turned over the trail thigh
Drills that fix it
Chest over the trail thigh · 10 min · 15 reps
Eliminate the reverse pivot by loading the correct side Make slow backswings until you feel the pressure in the inside heel of the trail foot and your chest turned over the trail thigh. Hold for 2 seconds at the top, then swing down. In the mirror, the head must not tilt toward the target on the way back.
Frequently asked questions
What is "Reverse pivot" in the golf swing?
Face-on: at the top the weight is on the lead foot and the spine tilts toward the target; on the downswing the weight falls backwards.
What does reverse pivot do to the ball?
The weight sequence runs backwards: weak, high shots, thins and a slice; compressing the ball becomes impossible.
How do you fix reverse pivot?
At the top, feel the pressure in the inside heel of the trail foot with your chest turned over the trail thigh
Sources
Titleist Performance Institute — Body-Swing Connection screening