Knuckle change.
you would think they would pick the grip if it was a change up? but it could be....
How do we know it is a change (knuckle) from this still shot?
Does anyone know where her index finger is on this pitch?
Being as I'm always wrong when it comes to pitching anyway, I'm going to throw my 2 cents in. I think that is her version of a knuckle/riseball. Instead of the front finger creating the spin, I think she is using her middle two to do it. JMHO.
Edit to Add: It's extremely difficult to tell from a still picture versus a .gif or slo-mo full motion video.
Dangerous pitch to try at her level of play.