The Ukrainian churches that previously used the Julian date for it had already moved to the Gregorian one, partly so that all of Ukraine’s churches celebrated it together on the same day. You’re correct about the public holiday; the government just followed suit and reflected the churches’ move with the public holiday
I’m surprised that the date of Christmas is under the government’s jurisdiction
Edit: I guess they can influence when the public holiday is
The Ukrainian churches that previously used the Julian date for it had already moved to the Gregorian one, partly so that all of Ukraine’s churches celebrated it together on the same day. You’re correct about the public holiday; the government just followed suit and reflected the churches’ move with the public holiday