I thought there was some anti-trust ruling in the last couple years that schools could no longer arbitrarily treat May 1 as a final commit date or maybe it was that schools could keep competing after this date to flip students. How does this work exactly?

The colleges want students to commit by May 1.

Jane Smith commits to College B. College A wants Jane Smith at their school though. They come along after May 1 and offer Jane a lot of money to come to College A. Jane is free to go to College A if she wants to, and she will probably lose her deposit at College B. College A has done nothing wrong.

I haven’t yet heard of this happening, but I am sure it has. Perhaps some athletes have experienced this?