Tell her right when the landing foot touches down, be on a slight backwards lean and push herself backwards with the stride knee at release. Cant push yourself backwards if you are standing straight up or leaning forwards. Just push backwards 6 inches or so, thats all you need.
She's probably trying to guide the ball too much in a game after time off from the injury. Maybe she's afraid of walks right now? Rememeber games aren't the same as practice. My DD has a pretty nice swing right now in practice, in the cage or at her hitting coach but she's delevoping a bad habit of steping in the bucket against live pitching that we are trying to work on breaking before it gets too ingrained. Probably best to talk to her and her pitching coach. Maybe come up with a trigger word like "stay tall" when you see her doing it in games.
If she only does it in games she's aiming, as mentioned above. The solution here is to convince her to throw as fast as possible and stop caring about where the ball goes. Accuracy is the product of consistency in practice, pitchers can't make it up on the spot.
Busted! Record her and show the video to her PC. Ask DD about it and show her the video. Ask her if she was aware she was stooping and what she thinks about it. Something she'll either need to self correct, or work it out with her PC.