It's well known that the current government had very low support until the war started and people realized that they had exactly the kind of leader they needed during wartime.

Support is much higher now (here, right after the war started: https://www.newsweek.com/ukrainian-support-president-zelensky-skyrockets-amid-russia-invasion-1683238)

So "was" is correct. "and is" is completely, utterly, outrageously wrong.

That there would be a huge boost is unsurprising. In the United States, President G. W. Bush had vastly higher approval rating right after 9/11 than before. And he didn't even have the bravery and charisma of Zelensky.