Last civil conflict in Russia was the second Chechen war.

By all definitions it's Ukraine in the state of civil war, not Russia. More than 90% of Donbas rebels are Ukrainian citizens. Russia of course supports the pro-Russian side in this conflict, but foreign interference during civil wars is so common, you could call it a rule.

And even outside the war zone you can see a strong polarization in Ukrainian society (just look at the recent news about an attempted murder of an opposition party member by far-right nationalists), with nothing comparable in Russia.