It's not good that you are uncomfortable when it asks you to talk about it with its preferred pronouns. It's 2023, it's about time you try to do what it ask you to do. When it tells you its preferred pronouns, try as hard as you can to follow it.
"It" has a pretty clear meaning in English, and it is not as a pronoun for people.
You seem eager to reduce this to "just" a pronoun issue, but it's not the same as calling someone "he" or "she", whatever they might prefer.
No one gets to single-handedly (re)define the English language for everyone else. "It" in this usage does not fall in to normal English usage, other than to mock people. That they want to use it nonetheless or whatever reason, that's fine with me. I will always listen to that and do my best to oblige with that within reason. However, radically different meanings for words in common grammatical structures, for me, falls outside of "within reason". Other people may choose different, and that is fine too.
In the absolutely fantastic novel Too Like Lightning there was a character that is famous for the life-like dolls made of it. Eventually it comes to term with the fact that its preferred identifier is "it" because it feels more comfortable being referred to as a doll, or inhuman, i.e. literally objectified, than it does with being considered traditionally human.
I also feel uncomfortable using "it" as a pronoun, luckily this person seems comfortable with "she/her" as well so we can just use those instead.
Maybe it’s something well know in the us/ gay sphere, but what does it refer to? I get to call the person he/she backwards so she/he feels acknowledged, I get calling one’s/they instead of he because it may be a woman and they will feel discriminated. But it referring to a person?
As an older trans person who's been subjected to targeted hate speech in public, I used to be pretty uncomfortable with younger trans people using it/its pronouns. It's understandable, let's give people some grace.
No one is obliged to endure morally sane discomfort for the sake of someone else’s comfort.
This isn’t “I don’t want to call her him because he’s a she.” The person you’re replying to has a very valid discomfort with reducing a person to an object’s pronoun. Completely understandable and defensible and beyond the apparent needs of the author.