If they’re a non-hetero person and you use it casually, I highly doubt they’ll give a shit. If you use it like a pejorative, then is one. Like the word “Jew”. That’s the common word for those in that religion/ethnicity and very often used to self identify. But in certain contexts with certain intonation, it’s understood to be a slur. The N word is less polite even among black people, but it’s still a common word used to self identify for those in the black community, but is still very much a slur when used by those outside the community. Calling someone a genius can be a compliment, or an insult depending on context. Both can be true.