Former President Moon is not happy about the criticism his administration has received from the current President:

Former President Moon Jae-in has said his administration established a system to counter North Korean drone infiltrations, according to officials of the main opposition Democratic Party.
Moon made the remarks when DP leaders visited his home in the southeastern city of Yangsan on Monday, apparently in response to criticism from President Yoon Suk Yeol that the North’s recent drone infiltration revealed how Seoul’s military readiness and exercises have been “greatly lacking” over the years.
“Former President Moon said the government had introduced radars and prepared substantially with regard to countering drones,” a DP official who met Moon on Monday told Yonhap News Agency.
Yonhap
You can read more at the link, but I have seen no one criticizing the detection capability. Clearly the ROK military did a good job detecting the drones which Moon’s administration should be given credit for acquiring. However, the inability to shoot them down to include crashing one of their own aircraft is what the criticism of the ROK military has been about.