Her front hip is going backwards so little bend in knee is ok. Damn is she powerful. Love her tempo.
I don't agree with your conclusion. A leg doesn't have to be locked out completely straight to be rigidly accepting a weight shift. That said, I would agree that If the leg is flexing and absorbing energy, instead of transferring that energy to the swing by providing firm structure, it can be a problem.
I didn’t say completely or rigid. But minimal would be a good description.
Since that is the case. I would try to harness the rotation a bit better. Since that is the primary source she’s uses for force production. Make sure shes got good direction to channel that rotation.
I won’t say anymore. Just an observation. Or how I would approach it. Good luck.