Starrys Obazei/December 14, 2022.
There are several reasons, according to Quora.
First, they do not want to escalate the war
Second, all of the resources at their disposal are needed to defend Ukraine. Attacking Russia would deplete those resources.
Most importantly, the war is unpopular in Russia. Putin is losing support daily. The partial mobilization has made the war hugely unpopular. An attack on Russia would unite Russians in ways that Putin has been unable to do.
Don’t interfere when your enemy is defeating itself. Particularly when they are doing a good job.