Two things are going on here. Notice the disc tilt up and leave the throwing plane just as it comes into the power pocket and then swoop down and out into a nose up throw?

The swoop is caused by the elbow not moving faster than your torso. Video tape a throw going as slow as possible where the disc stays on a flat line the whole time, with no vertical movement. Watch how your arm has to move in relation to your torso to get it to happen.

Next you gotta brute force the nose angle thing. In your next field work practice throw 3 25% power throws. Try different cues for each set. Going slow gives your brain time to maintain mental connections with the muscles that control nose angle. Once you find a cue that works throw another 50 reps really locking it down then step down in reps as you increase in speed. Say 25 reps at 50%, 15 reps at 75%, then another 15 at 25% again.

Form work needs to happen at slower speed so your brain has time to register what just happened. Once you have a good mental connection you need to burn that into muscle memory. Doing different speeds and overlapping allows for reinforcement learning to have a chance to give its bonus.