Abuse?

I would not call this abuse. I would call it bad and ineffective riding.

Hitting and booting the horse after it has already stopped is ineffective. She doesn't beat the animal, but rather than punishing it for stopping, she should have increased the strength of her aids on coming into the fence to commit it to the jump.

That said, horses at this level don't often do this - I hope she had him checked out afterwards for a sore back or similar.