Not the op but I’d assume the cruelty without repercussions leading to an actual response by the oppressed that will be deemed an “uprising” resulting in a “justification” to call in the army or something on whoever they want to blame.

Probably with a massacre or two, like, a traditional bloody one.

Not the slow behind the scenes killing off of people through deprivation of services, rights, due process with some old school SS thrown in, just in case; that ones building up just fine on it’s own.