it's 4am I'm gonna analyse the zomst designs
Ok so the thing that strikes me the most about Sua compared to her Alien Stage design is that... It's very similar. The core elements stay: a blueish white dress, a big center bow, puffy sleeves that become gloves, a white head accessory to keep her bangs in place and contrast her hair. The main element that changed is the puffy skirt ; basically, the outfit is pushed on the cute idol side, but it's essentially the same.
There's also how the infection affects her: it invades her face much less than Mizi, allowing her to keep nearly her full range of expression (and seemingly part of her mental capacities). However it seems to go deeper in her body (her leg's good as gone), diminishing her perfect idol image.
(also one could mention Sua's long hair is typically associated with her restrictive childhood in alnst)
Now yknow when I said Sua's outfits were very similar to one another? Well Mizi's the exact opposite. She goes from a black dress, high boots, a generally mature look and a really good color balancing (the blue hair tips that she asked for herself!!) to a design so PINK it hurts. there's nothing but pink - not even black or white accents. Every part of her design that wasn't pink was removed (such as her eyes). It's a very childish looking outfit (the pigtails, the big puffy skirt, THE VERY PINK VERY MONOTONE LOOK), yet it's also very sexualised.
It's a denial of Mizi's identity. It's the naive front she put up during alien stage, with her image as an attractive girl who can use her charms to get by (like in the witch comic). It's also seen with her infection: it doesn't cover her body, which is desirable, but it nearly entirely covers her face, notably her eyes. If in Alien Stage she was turning a blind eye to the reality of the competition, in Zombie Stage her sight has literally been removed, and she's barely aware of what's going on around her.
And I think the fact Sua and Mizi's designs communicate such different impressions is also an indication of their dynamic. Sua changed a lot, and is subjected to the idol industry, but she still retained parts of her identity. She's still herself, as much as she can be. Meanwhile, Mizi's a husk of herself, who can't even react to her surroundings anymore. And Sua has no problems with this situation: her love for Mizi became such an obsession in the end, she stopped caring about who Mizi actually is (was?), if it meant they were technically together.
