The Russian army is not used for policing inside Russia. At best that would be Rosgvardiya and only in cases the local police are not up to the task. When they did try to use Soviet Army troops to quell dissent in Moscow before the Soviet Union collapse that did not work that well either.Russia needs to keep back at least token forces to forestall a color revolution at home.
"Not that big". Compared with what? They also have at least twice that number of professional soldiers.It's armed forces aren't that big. The main reason why they can only commit 200k is because a draft historically is unpopular.
"Only for 1 year" is more than most countries.Finally, there is the question of conscripts' effectiveness, as the draft is only for 1 year in Russia so most conscripts are probably complete newbies who don't know how to fight.
I would not call the current situation a stalemate yet.With a full mobilization of Russian society, it can immediately call on 2 million reserves and the fighting-age manpower of Russia is 21 million, so there is little doubt that Russia would be able to win the war with full mobilization. Ukrainian society is already throwing everything they have at the war and they are barely keeping it a stalemate. The question is whether Putin is willing to take the risk.