MBC's 'King of Mask Singer' faces harsh criticism once again after inviting another guest previously embroiled in a controversy after the show invited Horan in the previous episode. The show received backlash when Horan, who has three DUI charges, appeared as a special guest in the episode that aired on April 9.

Then on April 16, Cao Lu appeared on Korean broadcasting for the first time in three years through the latest episode of 'King of Mask Singer.' On this day, she shared that she had returned to China and spent time with her parents. She explained, "After my contract ended and my work finished in Korea, I spent a good time with my parents. I worked in Korea for 14 years, and I saw that my mother's hair was greying, so I thought I should stay with her. I missed Korea while staying in China."

Despite Cao Lu's return to Korean broadcasting, netizens are not too welcoming. This is because Cao Lu was previously embroiled in a controversy over her social media post back in 2016. In 2016, she posted a photo on Weibo expressing that the South China Sea is China's territorial waters and wrote, "China cannot become smaller." This was a protest against the Philippines' decision to support the Permanent Court of Arbitration (PCA) in the dispute between China and the Philippines over territorial claims in the South China Sea.

Viewers and netizens recalled the controversy over Cao Ku's social media post and criticized 'The King of Mask Singer,' saying, "They allowed DUI Horan to appear last time now, they allow Cao Lu who protested against the South China Sea ruling appear."

Aside from this, some netizens were dissatisfied with the fact that Cao Lu appeared on the show wearing a Hanbok and commented, "Cao Lu appearing on the show wearing Hanbok will help with China insisting that Hanbok is Chinese" and "If there aren't more guests they can invite, they should just cancel the show."