Russians can’t even fight off Ukrainian mud and tractors.
Even though it maybe way more costly and slower going than the Russians expected, due to a valiant Ukrainian resistance, it would be wrong to say that the Russians are losing. They don't want to obliterate the Ukrainians or pay to rebuild the infrastructure if they bomb Ukraine back to the stone age so they are limiting their offensive operations. They probably don't want to fight it out building to building in Kiev and the other big cities, either, so my guess is they plan to surround them and starve them out. It's all going to take a while.