What? You didn't know? They secretly exterminated 6 M russian citizens on a secret 4x4 lab buried deep in Mariupol! And if you need more prove, they are fighting against Russia, they are fascists!!!
Ah yes, because there definitely wasn't some other common characteristic to the (not only leftist, as you carefully avoided mentioning) parties that were banned
Something like, I don't know, supporting the country actively invading Ukraine, perhaps?
Edit: so I figured I go investigate for myself and by "Ukraine" you mean random citizens involved in what was basically a civil war, the people in the building were using it as a fortress, and blockaded themselves inside, and by "people" you meant Russian separatist insurrectionists, who were firing from the building and throwing Molotov cocktails into the crowd below.