Herbert Marcuse was generally pretty ant-Soviet and started the trend of scholars deriding the proletariat in America, which I always found to be pretty bad.

Very much so but this goes right to the sorta second wave of then-leaders of Frankfurt School, specifically Horkheimer and Adorno, in the era post Walter Benjamin and Erich Fromm et al. Horkheimer worked very hard to suppress mentions of things like class conflict in what other Frankfurt School theorists would publish in order to efface the materialist underpinning of Marx-inspired analysis and it's no coincidence that the Frankfurt School retreated into really pretty sordid cultural critique imo and there's an argument that Horkheimer could have actually intervened to rescue Walter Benjamin from the fascists but decided to leave him to his fate, although the primary source is an academic work in German so I haven't been able to verify this directly myself.

Tbh that second wave of the Frankfurt School in exile was extremely disdainful of the proletariat and of Marx while they actively courted the bourgeoisie by adopting a pseudo-Marxist revisionist angle.

What is now happening to Marx’s theory has, in the course of history, happened repeatedly to the theories of revolutionary thinkers and leaders of oppressed classes fighting for emancipation. During the lifetime of great revolutionaries, the oppressing classes constantly hounded them, received their theories with the most savage malice, the most furious hatred and the most unscrupulous campaigns of lies and slander. After their death, attempts are made to convert them into harmless icons, to canonize them, so to say, and to hallow their names to a certain extent for the “consolation” of the oppressed classes and with the object of duping the latter, while at the same time robbing the revolutionary theory of its substance, blunting its revolutionary edge and vulgarizing it. Today, the bourgeoisie and the opportunists within the labor movement concur in this doctoring of Marxism. They omit, obscure, or distort the revolutionary side of this theory, its revolutionary soul. They push to the foreground and extol what is or seems acceptable to the bourgeoisie. All the social-chauvinists are now “Marxists” (don’t laugh!).

—Lenin, The State and Revolution

And yes, it seems to be in relation to Goerg Lukacs' humanism, not Raya Dunyayevskaya's.

Ah, not so bad then.