You cannot put anything pass the Korean left, so them trying another impeachment scheme is definitely plausible:
The presidential office lambasted the main opposition Democratic Party (DP) on Monday for spreading false rumors about the government allegedly planning to declare martial law.
Presidential spokesperson Jeong Hye-jeon condemned DP leader Lee Jae-myung for raising the allegations during a live broadcast meeting with ruling People Power Party leader Han Dong-hoon on Sunday.
“We are appalled that the leader of a major political party would spread fabricated rumors on live television,” Jeong said in a press briefing. “If there is even a shred of evidence, please present it.”
Jeong questioned whether the DP is spreading the rumors as part of a broader propaganda campaign focused on the radical idea of President Yoon Suk Yeol’s impeachment, vowing to sternly deal with its attempts to manipulate public opinion with baseless claims.
“Is this part of a buildup to (Yoon’s) impeachment?” Jeong asked, adding that if there is no evidence, the DP should be labeled a “party of fake news.”
You can read more at the link, but what is even stupider about this claim from the opposition party is that if martial law is declared by Yoon, by law the national assembly can overrule it with a majority vote. Currently the opposition party holds the majority of the seats in the national assembly.