most of the instances I could find were filled with liberal centrists who call themselves leftist, and hate actual theory-reading commies.
something politically like lemmy.ml or even like lemmygrad would be perfect.
it also shouldn’t be heavily defederated against
I’m not sure what you mean by Marxist anarchists, as Marxism and anarchism have dramatically different frames of analysis, but in communist parties Marxism-Leninism is the most common tendency globally. Are you specifically referring to authors? If so, then you may be closer to the truth if we only consider English, but if we consider non-English languages Marxism-Leninism becomes more common.