Their money is devaluating with inflation and they can't but another stable currency to mitigate the losses. Everything they import will be rocketing as it is, and it will be a case of paying for your Vodka when ordering in the bar rather than on the way out when the price has shot up.
Eventually there will be hyper inflation if the war continues, and Russia runs out of trading partners, the country will be in debt an they will print money without the economic resources to back the currency up, and then everyone's savings become worthless rubble.