I'm researching on this topic and found the following if anyone is still interested.
1. https://travel.state.gov/content/travel/en/international-travel/International-Travel-Country-Information-Pages/SouthKorea.html
TOURIST VISA REQUIRED:
No – From April 1, 2023, to December 31, 2024, the Korean Electronic Travel Authorization (K-ETA) is not required for US citizens traveling for short-term business or tourism purposes.
https://overseas.mofa.go.kr/ie-en/brd/m_23773/view.do?seq=761699
2. https://overseas.mofa.go.kr/ie-en/brd/m_23773/view.do?seq=761699
K-ETA will temporarily be exempted for 22 countries from 2023.4.1 to 2023.12.31. Please check the attached "Notice on Temporary Exemption of K-ETA."
(the notice is under the FILE section toward the top of the Page)
