I think his mechanics on that step-back are fine.
IMHO, Shaedon needs to live off his drive and midrange first, giving him more time and space for his 3.
However, he needs to do two things to take full advantage of that.
1. He has to get a better handle. His dribbling in tight quarters is below-average for a guard, even a shooting guard. Now, he's great when he has a lane; he's almost unstoppable when he has a runway. His problem is when the defender cuts him off or a help defender gets a hand near his dribble. He hasn't mastered the change of pace and changing height of the dribble and then the moves he can do off that.
2. Just what I'm seeing from Shaedon is consistent with players I've coached or observed that don't have great offseason workout habits. He shoots with great form. He's done that since high school. Early in his pre-draft year, when I was really amplifying drafting him because I thought he had a good chance of being not only the sleeper in the draft but eventually the best player in his draft, it was because his shot tool was pure. I didn't even realize at the time how much bounce he had. But, man, could he shoot both off the catch and the dribble. It just looks to me like he needs to shoot a lot more in the offseason. He needs to see the ball go in cosistently, like the workouts we saw Scoot doing. He needs to see the ball go in consistently with defenders there to distract him so he learns to shoot in games the same way whether defense is there or not, so he gets a feel for how much space he needs to get his shot off the same way every time. I also think conditioning might be part of this. There are times when he just settles for easy 3s really early in the clock. Those are shots you hope go in but not shots you expect to go in.
I'd love to see a video of a full offseason workout of his, because I'd almost be willing to bet they don't have the intensity that you see with the best players. That he's as productive as he is with such fundamental holes in his game makes it scary when you think what he could be.