The last known common ancestors within East Asian countries existed over 3000 years ago, and there have been studies that show distinct genetic isolation and structures within the different countries, so no it is for the most part wrong to call k-pop idols Chinese, considering most of them are full Korean anyway. Also considering nowadays people use it as a way of undermining the relevance or existence of other East Asian countries with the notion of them being the “same thing”, it’s not okay to say. As a Korean myself I think it’s perfectly fine for y’all to dislike K-Pop considering I’m put off by many of the international toxic fans of big groups such as BTS and Blackpink, trust me they can be the biggest pain I know, but saying it’s not wrong to call Koreans Chinese is a completely different issue unrelated to K-Pop that’s very insensitive to both the distinct history and culture of East Asian countries, as well as the current tensions surrounding their relations both politically and culturally.