Anyone noticed that it's only the audience that ever projects Sexiness onto her? That the only display of power (something you COULD characterize as sexy) is ever on intellectual matters, which she happens to be insecure about as we learned recently?
This isn't the game doing it in general, mind you. Rodya is very much The Baddie of the team. Ryoushuu had her own sex appeal also in relation to power. Outis is like 90% some kind of Badass Sexy in her IDs. Don Quixote has her own thing going on with her energy (and the contrast with Sancho, which, again, Power).
Don't get me wrong, Faust has her attractiveness, but it's always in the realm of "dork with a pretty face" (and like what character DOESN'T have a pretty face in the main cast?) which is very similar to Yi Sang, except he's very outwardly melancholic. She just happens to be busty? And Rodya is right there anyway.
If I hadn't seen this a lot I'd say it's just how things go with all fictional (and non-fictional tbh) women, but I know it's because she's -not- outwardly sexy. It is precisely because she's reserved.
Now, is there anything "wrong" with this? not necessarily. People calling it "fanservice" when she's fully clothed with several layers just because she has tits isn't just someone being horny, but projecting horny intent on a regular picture. I think there's a distinction between "reserved women turn me on because it's my thing" and the assumption that everything she does is sexual or "hiding something". The picture is "good looking" as in appealing to beauty standards, but it's not a pinup.
This is why I say maybe I'm projecting. PM absolutely makes their characters attractive on purpose, and they lean into -what- makes them attractive (See: Thumb Capo Meursault, basically every Rodya, Contempt, Awe Ryoushuu) and you'll notice that with Faust it is never about her body (in that sense), or how she interacts with other people, or whatever. The most obviously suggestive moment she has is with Ring Apprentice uptie story, like, it's incredibly horny, and it's precisely about the way She Behaves and not how she looks.
Am I saying "don't be horny about her"? No. I am saying the misogyny is palpable, enough that people are: 1) reducing her to "quiet girl with HUUUUGE tits" 2) getting horny about traits she doesn't have (because that's how the quiet girl fantasy goes) 3) ignoring the ones she DOES have that are there PRESENTED THAT WAY (how many times does she need to dig through guts (one time her own) for you to Get It), and this whole thing is so potent that The Baddie does not get that treatment, because she IS intentionally sexy, right? can't let empowerment be sexy, that'd mean too much agency* for a woman..
*You did notice that, right? That the ones that are in control of their attractive traits (all of them) don't get the same treatment? that the one whose whole thing is Not being in control, and is reserved, gets instead sexualized in terms that aren't her own? did you notice that? that she becomes the focus? of turning her into a fantasy rather than fantasizing about what she is?