As of my knowledge cutoff in October 2023, there are no official reports indicating that South Korean President Yoon Suk-yeol has been impeached, nor that any defense intelligence commander has been indicted over a failed attempt to declare martial law on December 3. President Yoon Suk-yeol was elected in March 2022 and has been serving since May 2022.
For the most accurate and up-to-date information, please refer to recent and reliable news sources.
Reference(s):
S. Korea defense intelligence commander indicted over martial law bid
cgtn.com