Authoritarians are going to authoritarian, whether they're right wing or left wing, in general they seek to centralize power in the hands of the few.
Sure they might have leftist economic policies but they still centralized around a singular figure who can do no wrong and everything perceived as bad they do is justified because they're the good guys.
There's a significant portion of leftists who align much closer to anarchist ideals, where power is as decentralized as possible, and they despise the authoritarianism of the pro-Stalin/pro-Mao/pro-Jiping tankies.