Are you talking about Xu Kai's phone call in Ep2? or there's more Korean-speaking scenes in Ep7-8?
Actually the phone call sounded alright, but when A-Tai spoke in Korean and also the interviewers, it just sounded a little awkward and off. I can tell because I watch many K-dramas but I may be wrong idk?
Basically, the author wrote the story based on real life people and real life events and the E-sports fans are mad because the 2 leads are dating without putting in effort. Basically they are saying that it's an insult to E-sports and the players and they don't respect them and stuff like that. You can scroll down for more info.