Fascism portrays itself as irreverent even as it represses dissent
Making Hitler funny may be a break with the reverence Hitler demanded at gunpoint. But it also ends up being a way to give Hitler back his aesthetics and part of his glamor. When Downfall Hitler launches into an attack on road construction, it's incongruous and absurd. But it's also Hitler getting you to cheer along as he attacks the incompetence and inconvenience of a sclerotic democratic bureaucracy—and attacking sclerotic democratic bureaucracy is a thing that the real Hitler actually did. A dollop of humor makes the anti-establishment rage go down easy, not least because it distracts you from the fact that the "establishment" in question is just anyone the fascists decide to target. As the political scientist Jonathan Bernstein explains, "drain the swamp" is a successful slogan precisely because it's a catchier way to say "liquidate our enemies." from Fascists Know How to Turn Mockery Into Power [Foreign Policy, from 2020; ungated]