His form looks good to me. I think his issue was his footwork, he doesn't always go straight up and doesn't have his feet in the same place consistently when he shoots. This should be cleaned up with repetition.
I think the biggest issue is people grading him after just 1 yr of college stats. The great shooter Buddy Hield shot what his frosh season ?
38% FG, 24% 3-pt, Averaged 25 minutes per game.
Brown ?
43 % & 29%, in 27 minutes.