If you gave Chloe a redemption how would Zoe fit? Not Vespera just Zoe...
I discussed this in more detail here, here, and here, but canon Zoe has all the hallmarks of a Mary Sue. She shows up out of nowhere in the middle of the show and immediately becomes close to the main cast. She has no real flaws. Everyone loves her. She gets a romance arc with the main character. She's the only person other than Adrien to wield the black cat miraculous. You get the picture. She's the kind of character I expect to see as an OC in a fanfic, not an actual character in canon.
While I will defend the rights of Mary Sue's in a general sense, a Mary Sue has no place in Miraculous canon. It's the wrong type of story for an idealized self-insert that the audience can project themselves onto for many reasons, chief of them being that those types of characters only work as main characters. This makes it impossible for me to use Zoe as-is. I'd have to completely redesign her character so that she had depth and flaws and I have no interest in doing that.
It's not that I hate Zoe, it's that she has no reason to exist outside of being Chloe's perfect replacement. Take away that role and what is she even doing here? What purpose does she serve that you can't give to one of the twenty other teenage characters that canon already introduced!!! And that's not even counting the specials which introduced another three for some reason. Writers, what are you doing? Stop adding characters!!! You need depth, not breadth!!!
In theory, Zoe could be used as part of Chloe's redemption, but that would require them to have an actual bond. As best I can tell, in canon, Chloe and Zoe didn't meet until the start of season four. They're sisters in the biological sense, but that's about it. This once again makes it hard to see Zoe as value added.
If the Kwamis didn't exist and Zoe was Chloe's cool older sister, then she'd have some potential as Chloe's mentor, basically taking on the role I see Pollen in. She'd also have potential as a significantly younger sister who adores Chloe, making Chloe act nice because she wants to keep that adoration. But Zoe is none of those things. She's basically the same age as Chloe, Chloe doesn't care about her, and Adrien already fills the role of Chloe's same-age sibling who grew up in a different home, so why would she need another one?
Another theoretical path for Zoe would be to let Chloe redeem Zoe. We know that Zoe was a massive liar in the past. If she was introduced while still in that phase, then redeemed Chloe could show off her new skills by helping her sister. It would even give you a nice way to address how messed up their mother is.
As nice as that may sound, I still wouldn't go there unless Chloe was my main character. Zoe's redemption just eats up way too much screen time as you have to establish who she is, give her a relationship with Chloe, and so on. Not a quick little addition to the script and not worth the time when her only purpose is fleshing out Chloe. There's also the Sabrina issue. If Chloe is going to redeem someone, it feels silly to add a whole new character when you have an established character right there, ready and waiting. Writing wise, Sabrina feels way more like Chloe's sister than Zoe ever did so why add Zoe?
No matter what way you look at it, canon Zoe just isn't needed. There are no missing roles that she's ideally suited to fill. You'd have to totally redesign her to make her work and, at that point, you're not using Zoe, you're using an OC with the same name.
