Before the latest Russian election one of the parties opposed the war in Ukraine and was a bit too popular, so, well, from https://en.wikipedia.org/wiki/Yabloko :

  Yabloko is the sole officially registered party to openly oppose the Russian war in Ukraine, openly calling "for peace and freedom". The party planned to partake in the 2026 Russian legislative election under their anti-war slogan.[29][30] However, in August 2026, the party was barred from running by the Supreme Court of Russia due to a lawsuit by Rodina.

Also, several politicians associated with it were imprisoned, e.g. this guy: https://en.wikipedia.org/wiki/Lev_Shlosberg