While the parties that Zelensky banned were not all left wing (opposition platform for example was a coalition of parties across the spectrum), they were not pro-Russia either. These parties have all condemned the invasion. They were called pro-Russia because they wanted to have better relationship with Russia out of pragmatism and secure the rights of Russian speaking minorities in Ukraine. Zelensky was also elected to do the same. It is a centrist position. So now Ukraine only has far right parties.