The KCTU did not mind when the Korean left was demanding the prosecution and jailing of former conservative Presidents Park Geun-hye and Lee Myung-bak, but don’t like it when their political leader Lee Jae-myung is being prosecuted. Ironically they are condemning President Yoon for the prosecution when during the last administration he was the chief prosecutor that put President Park in jail which they championed. So what you can take from all this is that they only want conservatives prosecuted:
Members of a major South Korean umbrella union rallied in downtown Seoul on Saturday to condemn the Yoon Suk-yeol administration, jamming traffic in the neighborhood.
Some 13,000 union members of the Korean Confederation of Trade Unions, one of the country’s two major umbrella labor organizations, held multiple rallies in Daehangno, Saejongno and Jongno, in protest against “prosecution-backed dictatorship.”
During the rallies, the protestors said the country’s civil livelihood, democracy and labor fell to the worst conditions under the Yoon administration in less than one year of his presidency.
Yonhap
You can read more at the link, what is further hypocritical about the KCTU is that they are calling the Yoon administration a “dictatorship” while their union and the political left has been linked to North Korean spies. North Korea is a real dictatorship which the KCTU says nothing about.