Freed after serving his sentence, on 22 April 2022 (nine days ago).

He is not legally vindiacated in that his sentence was not commuted, pardoned, or otherwise reduced.

The Wikipedia article is vague on all of this, but Democracy Now states:

Last year, the judge in the case found Donziger in criminal contempt of court after he refused to turn over his computer and cellphone, sentencing him to six months in prison for contempt of court — a misdemeanor. In an extremely unusual legal twist, the judge had appointed a private law firm with ties to Chevron to prosecute Donziger, after federal prosecutors declined to bring charges. After 45 days in prison, he returned to house arrest — until Monday, when he finished his sentence and was released, after about a thousand days under house arrest.

https://www.democracynow.org/2022/4/26/steven_donziger_freed...

Donziger remains disbarred in New York state. His current campaign is to have the Ecuadorian judgement against Exxon-Mobil reinstated and enforced.

He got a lot of sympathetic coverage because of the goals of his campaign, but if you look into the details he is clearly in fact guilty of bribery, corruption, and fabrication of evidence in Ecuador. Do the ends justify the means? He was also likely going to make a huge amount of money, it wasn’t quite as noble as it seems.