So your main character or someone close to them is an ethnical or religious minority? Oh, they are also gay? That’s good; you have diversity in your book… Or do you?
Mentioning once that one of your characters is a part of a minority and never going back to that could be pretty insulting to said minority; they could view your character as a token.
So what if they are black, gay or Muslim?
What were the consequences for them?
How did it affect their personality, lifestyle and view of the world?
What difference does it make to your story?
Did your lesbian lead fall for her straight female classmate, changing the dynamics in their relationship? No? She’s openly gay and we never see her dating women, flirting with them or even just checking them out? Being homosexual never affects her or how others perceive her?
What about your character’s Muslim best friend who is crushing over a girl from a Catholic family? How did that work out for them? You are not showing us, even though this is your MC’s best friend?
You need to work on your characters. After all, what’s the point in making them different from the majority of people if we never see the outcome of that?
Don’t make your characters diverse just for the sake of diversity.