look, Asian (mostly Korean/Chinese/Japanese from what I understand) idol industry is fucking insane, one small scandal can ruin entire careers, it's not new.
For example, Japanese idol industry have love bans (this is kinda changing but is still very prevalent in popular groups) which mean idols can NOT date anyone at all. They're constantly being watched by fans and paparazzi, and many idols have been harassed/insulted just by being near a member of the opposite sex.
An idol from AKB48 had to shave her head to beg forgiveness from fans because she was ACCUSED OF dating. She still lost her idol career though.
Another girl,
Shasihara Riko was discovered dating in 2012 and got kicked out of her idol group AKB48, and transferred to another lesser group. She luckily still have a successful career after this.
more recently,
Uruha Rushia, a vtuber (online idol who use anime girl avatars instead of their real faces), got her contract terminated because... you guess it, she was dating someone! This was back in 2022 btw.
aside from the insane love ban, idols also have to be EXTREMELY careful with whatever they're saying, because people will twist their words to harm them.
In 2021,
Kiryu Coco, a super successful vtuber (who was honestly the most well-known vtuber back then) got terminated because... look, this will sound insane, she said the word "Taiwan".
For some reasons, Chinese fan think that by saying "Taiwan",
Coco is acknowledging that Taiwan is a country (she wasn't, she was reading some analytics thing on her channel and she noticed that she also had Taiwan fan), so they got
extremely butthurt. The newspaper in Chinese twist things up even further, and things got out of control way too quickly that the only way the company knew how to stop the fire is to fire
Coco.
Here is the more detailed post about this if you want to know more.
so yeah, TLDR: it's not about what the idol did/how serious the action was, sometimes one small mistake got blown out of proportion and boom, no more career.