However, saying it is a harem is the same as saying that JK Haru is a Sex Worker in Another World is your usual generic isekai since MC sleeps with adventurers, and that makes her an adventurer by proxy.
Because the MC is a member of the emperor's harem but hardly ever interacts with the emperor. The things that people look for in harem tagged stories are all absent.
It was in a different thread, and I don't remember who said it, but it perfectly explains my position. If you talk to a modern-day weeb who asks for recommendations, asks for an isekai, and you recommend The Chronicles of Narnia to that person, you will look like an idiot. Even though it technically fits, we all know that this is not what a weeb was looking for.
I may not understand it correctly, but she never was a member of the harem, she was a servant and never "rank up" to be in the harem selection pack. Not even mentioning the real harem or the true wives.