Ukraine’s constitution is confusing. Article 103 states that the president is elected for a five-year term; but Article 108 says that he or she exercises power until a new president is inaugurated. A longstanding law (though not a constitutional provision) says that elections cannot be held when martial law is in force, as it has been in Ukraine since Russia began its full-scale invasion in February 2022.
Having read about this before, I can say that The Economist is wrong. It is a constitutional provision in Ukraine.
They also banned or nationalized many media outlets, censor media in general, and suspended eleven political parties during his term, which eventually became permanent bans.
Noone in US or EU would care about expiration of Zelensky’s presidential term as long as he's reliable supplier of cannon fodder for proxy NATO-Russia war. Roosevelt's words on Somoza ("he may be a son of a bitch, but he's our son of a bitch') would apply here as well.