Stats from Sports Illustrated:

As of late May, more than 1,200 NCAA Division I softball players have entered the transfer portal this academic year, with over 500 of those entering since the portal re-opened on May 18.

The Division I softball transfer portal doesn't open for undergraduates until after the Women's College World Series on June 8, so the numbers are expected to climb significantly after that. Graduate students and players whose teams have experienced a coaching change can enter the portal at any time.