Zelensky wore a suit on his second visit to the White House, at the explicit request of the Trump administration.
This comes after he was publicly humiliated by Trump, his allies and some journalists during his first visit on February 28.

One of the journalists who had publicly humiliated Zelensky during his first visit to the White House, Brian Glenn, reporter for the conservative media Real America’s Voice and companion of Marjorie Taylor Greene, this time highlighted the fact that the Ukrainian president wore a suit during his second presence in Washington.
Live from the Oval Office, Glenn addressed him directly, while Donald Trump reminded Zelensky that this was the same reporter who had previously chastised him for not wearing a suit.

Zelensky replied that he remembered him very well, and wryly pointed out that Glenn seemed to be wearing exactly the same suit as when they met earlier!