I read somewhere that Noah doesn't play well under pressure, this does not bode well for his development.
In my opinion, it seems more like that only happens when he has people relying on him that he doesn't want to let down, like after Kozlov lost against Australia and the team needed him to win. Or when all his friends and family came to the us open and he didn't want to disappoint. I think he also lost a surprising match at the USA vs UK juniors event before Wimbledon. But I've never seen him crack under pressure when he's just playing for himself.
It's still something he needs to overcome though.
(also, we should keep in mind that during these instances where he plays bad under pressure, he is playing guys just as good or better than him like Kokkinakis here and Kyle Edmund at the US Open)