And the Russians are adept at fighting a winter war.
More than the Ukrainians, being that its their land and their familiar weather? Primarily its a matter of logistics, which the Russians seem to be utterly inept/corrupt.
Are they? Ask the Finns, or look at the death tolls of the invading German Army versus the native Russian Army in WWII, we don’t really see any winter finesse or talent from the Russians, just an indifference to human life.
Looking at this current war I would bet that Ukrainians will display more winter capabilities than the Russians, regardless of who wins in the end.