@Rias_Gremorys_Husband I think that the problem is not so much that her whole personality is literally the archetype of "arrogant butch lesbian", but that the arc does not affect it at all and does not give her any development. Even hinting that even after losing, she still has some chance, as Kuromu did not treat her negatively due to her behavior. In fact, it gave more development to Iruma himself, as he discovered the "Wicked Iruma" form, lol. But this arc wasn't even directly about him.
@BalrogDeMorgoth It would be funny if in the next chapter Kuromu hinted that she developed a crush on him after his help. It would be fun to read the reaction to that. But I doubt it will, given that the author hardly sees her as a love interest.
@immy A character suddenly bursts into the plot, whose whole personality is "stereotypical gay", her potential love interest (and all almost 200 chapters before that, the plot never even hinted that Kuromu, at least in theory, could be involved in something like that) remains tolerant of her all the time, regardless of the rudeness of her behavior, and the arc ends as suddenly as it began. I don't think this was a very deep development of the gay element.