SZ has been known as Eswatini since April 2018 (formerly Swaziland).
Sources:
https://www.iso.org/obp/ui/#iso:code:3166:SZ
http://www.un.org/en/member-states/index.html#gotoE
http://www.times.co.sz/news/118373-kingdom-of-eswatini-change-now-official.html
MFC after: 3 days