I think I understand why this story only has a 7.3 rating on a website with a rather forgiving rating crowd (relative to MAL, at least). If it followed the usual structure of the genderswapped FMC falling in love with the best friend MC right away, I'm sure it would've gotten a higher rating. Or if it at least didn't deviate from the cliche in a half-baked manner. The MC confessing to her right after she learned the side character doesn't return her feelings and then giving her a dumbass "challenge" didn't sit well with me. And then she decided to entertain said dumbass challenge instead of properly rejecting him. That b*tch at the end bit may have been a horrible person (and a homophobe), but she was correct about one thing-the FMC stringing the MC along. And then, out of nowhere, in the very last chapter, she falls for the MC after he protects her. As you might guess, this really didn't sit well with me.
Not to mention that it deals with gender dysphoria in a roundabout manner. I'd personally give this a 5-6. If you're interested in the genderswap genre, there are many examples that are better, and I would not recommend wasting time reading this (fortunately, it's a very quick read, so you won't be wasting too much time if you do read it).