Anyway! A problem I never could have anticipated is that apparently, she was based on an actual, real person -- at least, that's what one woman also named Seraphine claims. And she is not here for it.
This allegation stems from a few sources: while both the woman and the champion share a casual resemblance, given the pink hair, glasses, and love of cats, that alone is not enough to build a case. More convincing is the fact that she dated a Riot employee directly related to the K/DA project for a few months, who on several occasions, made allusions to her and the fictional band.
Riot, for what it's worth, has denied these allegations in an email sent to PC Gamer:
"Seraphine was independently created by Riot Games and was not based on any individual. Additionally, the former employee [Stephanie] is referring to left Riot more than a year ago and was in a department and role that has no input whatsoever into the creative design process."
How true this is can be debated. Characters in League tend to be in development for a while, so an employee leaving over a year ago doesn't strictly disqualify them for contributing. Additionally, it's already been stated that her lore is based off another real person, Jasmine Clarke, so the first part of Riot's statement is already provably false.
In any case, this is easily the most problematic character Riot's put out in a while. Between this, her skin-focused release, and the fact that she's canonically Chinese while her old lore directly implied she was complicit with the genocide of an entire race, players have had a lot to say about her.
Which has been a trip.