Do you mean the USSR and China? Because yeah, many leftists opposed those revolutions, including at the time (anarchists opposed the bolsheviks and were murdered, support for Mao fell off after the West learned about the Cultural Revolution). The mainstream form of the left nowadays is either reformist (social democrats like Bernie or AOC) or libertarian socialists/anarchists opposed to the state (David Graeber (RIP), Noam Chomsky).