The agentless passive is a sentence constructed so an action occurs without anyone performing it: things “are rolled back,” “have begun,” “were offered,” and the sentence never says by whom. It is not the passive voice in general, which has legitimate uses; it’s the passive voice specifically deployed where a named actor could have gone and didn’t. Orwell flagged it in “Politics and the English Language” as one of the standard ways political prose dodges responsibility for what it describes.