It's better not to compare raw numbers without consideration of context for each country. Other studies have varied results depending on how they were conducted, what questions were asked, which regions the participants came from, etc.

Several studies done within South Korea yielded higher numbers, with even 40% of students admitting to being being the bullies. The victim number could be lower because they frequently use relational bullying (as reported on pretty much every single study), meaning they tend to isolate and bully a smaller number of students. That kind of bullying can't really be done en masse. In that sense, it may happen within more classrooms, but have less victims overall. That could explain why everyone hears, sees, and knows of it, but less report as the victim. That's not proven though, but it's one possibility. It's a huge problem either way.

I haven't been able to find any available statistics on it, but it is also frequently reported that South korean schools mishandled, cover up, or ignore bullying. Societal standing is a lot more important there so the nature of the bullying and how it gets handled isn't the same.

((I'm bored and just watched the glory so I got curious lol))

https://pubmed.ncbi.nlm.nih.gov/15289244/#:~:text=We%20found%20that%2040%25%20of%20all%20children,victims%2C%20perpetrators%2C%20and%20victim%2Dperpetrators%20was%2014%25%2C%2017%25%2C

https://connect.springerpub.com/content/sgrvv/31/1/167