ILLIT recently performed at Sogang University’s festival.
Chaos ensued when a fan of NJZ (formerly known as NewJeans) publicly mentioned NJZ when ILLIT was preparing for their performance. The MC at the festival had asked if anyone had an upcoming important date, such as a birthday. Someone had shouted “NewJeans Haerin‘s birthday,” leading to boos from the crowd. Various accounts of the matter popped up on the school’s community board after the event.

It was silent for like 3 seconds after someone mentioned Haerin LOL.
— Anon

OP: “Summing things up for those curious about the incident with NewJeans being mentioned. Before this, the MC had been looking for people who’s birthday was that day, so we could congratulate them together.”
MC: “It appears that ILLIT is still not ready. In that case, is there anyone here who wants to be congratulated for something, even if it’s not a birthday?”
Fan: “Me! It’s NewJeans Haerin’s birthday!”
MC: “Who? Oh, NewJeans’ Haerin. It seems like there’s some booing and criticism going on here and there. We’re not looking for things like that, but I’m talking about if there’s anyone present here that wants to be congratulated for something. Is there anyone? Oh, over there! You’re enlisting next week?”
The fan was chewed out heavily on the community for being a disgrace to the school and a nuisance to the performers.
I wonder if ILLIT heard. They’re such a nuisance to the school.
— Anon
Given the situation that surrounded ILLIT and NJZ, the student’s mention of NJZ during ILLIT’s performance was seen as rude and inappropriate.