I saw this happen very rapidly in the 1990s. I worked in a council that for years had a reputation as frugal but efficient. It was "humming" with a public service ethos. A change in political leadership brought in a series of "diversity hires" , they in turn hired "their own", in a shockingly short time (3 years) the council was wildly overspent, one diversity hire was on "gardening leave" another "let go" due to incompetence and some services in "special measures" . And the public service ethos was gone in favour of "mind your back" because if course the incompetent have to defend their failures by blaming all around them.