I think they are referring to the anti-liberal authoritarian left wing that has gained a foothold not only in the DNC but into the mainstream culture in certain ways. But "left-wing fascism" is a thing, or at least and idea, that has been around for awhile. Some call it "red fascism" and is in reference to left wing ideologies that are far from the center. It sort of invokes "horseshoe theory" that says left and right get pretty similar the further they get from the center.
