Kazami actually had character development - he went from the dudebro who wanted to solo anything to understanding the importance of being a team, represented by his upgrading from Justice Knight to Aegis Knight, because Aegis is what connects the other three MS for RE:RISE Gundam.

Miko had zero development.

After having a look at both Kazami and Miko character-wise, I do find out my biggest problem with Miko as a character, that'll be despite her initial characterizations opens up quite a bit of growth and character development..... she never actually grew as a character in a way that actually matters.

Unlike Kazami, Miko never suffers any consequences because of her reckless actions; Kazami actually suffers the consequences of his insensitive actions (that causes the complete annihilation and the deaths of a huge number of local Eldorans) in the worst way possible, which makes him truly realizes that all of this wasn't some stupid game anymore; and actual lives are at stakes.

Unlike Kazami, every single lesson Miko learned never actually sticks within her and changes her in a way that matters; Kazami actually feels great remorse for his previous selfish antics, and actually changes to become a more selfless, heroic person that actually fights alongside the BUILD DiVERS to defend Eldora.