@inchide, you are totally forgetting the crucial part of what is exactly means to switch the genders - it doesn't really matter at which point this thing happened, as long as the gender of some characters stopped being canonical it means that gender-bender already happened. Here both of those characters become gender-bendered in comparison with their parodied male prototypes Ash Lynx and Eiji Okumura from Banana Fish, instead of being "almost" gay couple they become a female yuri couple, not to mention that originally there weren't any catboys/catgirls.
This Azul group and many other circles also have some My Hero Academia doujinshi with coupling of female(originally male) Izuku Midoriya x Katsuki Bakugou(male, sometimes becomes female while Izuku's gender stays being original aka male), similar things happened in hundreds of doujin parodies of Detective Conan/Kimetsu no Yaiba/Naruto/Kuroko no Basuke etc. where some close male friends/frienemies/mortal enemies become a coupling of MxF/MxF to FxM/MxM to FxF or even FxF to MxM(some rare thing), once again it's still a gender-bender even if the transformation wasn't shown in doujinshi at all as what is really matters is their original gender in source novel/manga/anime.