I would hope that ROK counterintelligence agents would be keeping close tabs on any ROK Soldier with ties to China to prevent spying like this:

A South Korean soldier raised in China has been arrested on suspicion of leaking classified military information about joint U.S.-South Korean exercises to Chinese intelligence agents, prosecutors said this month. The 22-year-old army supply specialist, whose name has not been released, was arrested April 18 and charged with leaking military secrets and accepting bribes from foreign agents, according to a redacted indictment filed May 15 by the Military Prosecutors’ Office in Gangwon District.
Prosecutors allege the soldier transmitted information — including details related to Ulchi Freedom Shield, a large-scale joint military exercise with the United States — to China’s Intelligence Bureau of the Joint Staff Department. The leaked documents reportedly contained sensitive details such as base names, troop schedules and logistical capabilities, along with participating troops’ personal information. The soldier allegedly received about $12,215 via the Chinese digital payment platform Alipay, according to the 15-page indictment.
You can read more at the link, but this guy had major red flags, he was raised in China by his grandfather who is a retired Soldier and went to college in China as well. While serving in the ROK military he made repeated trips back to China.