...is very cold , fortunately I'm in the UK at the moment where I stumbled across this war trophy in the grounds of the local museum. The cold in Ukraine has coincided with a lot of snow cover so most plants should be OK assuming temperatures lift to a more seasonal minus 10 some time soon.
Cold in itself is not an issue so long as there is some insulating snow but much of Ukraine's winter plantings went in to the winter in a weak and underdeveloped state so they will be at more risk.
The Min of Ag is suggesting losses up to 35% which I think is high, 20% would be my estimate.