Some of the more extreme-minded liberals do a good enough job at sabotaging themselves and the movements they are a part of, without the need for malicious saboteurs. Like Atheist+ or progressive stack.
Then again, Russians orgs are out there, trying to influence politic movements and sabotage others. GamerGate was an entire sea of political actors, journalists, influencers, and Russian agents, trying to push their own narratives to the point of mass disinformation from both sides, with the general public on either side confused and angry at the other's responses.