Galloway's shot mechanics are an issue, but this is hardly a new discussion.
Has anyone noticed, you ask? Yes, when he was 15. I'm sure he has worked on his shot repeatedly to smoothen up his mechanics, but it's hard to transition a jump shot. You really have to shut down and just work on that, otherwise old habits creep in.
When I finally decided to change/better my release point, (age 13) I dreaded it, & knew it would take a (relatively) long time to fix/change, & be successful with. If I recall, it took me the better part of a year to do, be comfortable/natural with & successful with. Now, just picture a successful/good/very good hs or college player taking off a year/season (& all the bad shooting stats that go with that year), or even sacrificing a year. I think that is why so many hs & college players either never change their shot mechanics, or put it off far, far too long. Your shooting % stats will suffer mightily in that year, & the people offering you scholarships, pro $$$, & the like, might just decide to go after someone else?
Bottom line, the longer they wait to change their shot, the tougher it is, & the more costly it is, in more ways than one.
Btw, you mentioned "...it's hard to transition a jump shot." The best way to do it/the way I did it, was, start with your set shot. First close in, then when you've gotten good at that range, move a little farther out, & so on, & so on. I did work in a little jump shooting in there, but it's much easier to get the set shot fixed first. Once you've mastered the set shot, then begin to transition to your jump shot, with your new & improved release point in full use. Once you've improved your new shot to around 15', the free throw line is a good place to practice from there.