Good analysis! At first I was just chalking it up to undisciplined (i.e., bad) teams playing badly and getting punished as a result. But the increase in impactful penalties called in the 4th is oddly both higher and broadly consistent in terms of rate.
But I also find it interesting that it doesn’t correlate very strongly with overall team records. Some of the best teams are among the more punished, and some of the worst teams are among the most benefited. It impacts individual games, but not individual teams. If I gambled, I would be concerned.
Didn't run it, just looked at the data. You laid things out really well so the visualization on its own was enough to get an accurate feel just by looking. So kudos goes to you really!