The Bad Batch state that the Wookiee village was razed by Imperial tanks, and upon seeing the slavers, identify their hardware as Imperial and question how they could've gotten their hands on it. The tanks shown are Separatist, not Republic/Imperial.
One of the security droids derisively refers to Omega as "humanoid." Humanoid just means anything with a human-like shape. As the droid itself has a roughly human shape, it fits the definition of humanoid.