The common thread of 'authoritarian' countries isn't communism or fascism. It's having significant opposition. Almost always from the US.

No Communist supports suppression of dissent. It's a countermeasure to foreign interference. It doesn't exist because tankes feel like authoritarian states work better but because the US has an extensive and well known track record of breaking international sovereignty laws and installing fascist regimes by force.

Communists didn't want to be slaughtered for wanting to abolish poverty. Therefore every real life communist is a tankie, either because they understood that class war is war or because they're buried under capitalist soil.

This suppression of opposition doesn't have ideological basis. It's an emergency measure in a time of war. Hence why even every CAPITALIST country opposed to US interests is 'authoritarian'.