There’s no authoritarianism like that observed in leftists ideologies because they insist that they’re inherently incapable of being authoritarian, or that their extremism is simply humanitarian.

Importantly, any group that perceives an existential threat will favor extremism, regardless of their underlying ideology. The problem is when they flag false positives, or conflate the activity of healthy democratic activities or institutions as subversion.

Ideas will always be open to challenges in a democracy. The unspoken secret is that all ideologies prefer authoritarianism after they’ve gained majority support as their primary goal is support for their in-group, and disadvantaging their perceived enemies.