I don’t think a cop can psychologically hold up being on the street for years on end without losing some perspective. The job fundamentally blasts you with the worst of people, and it’s easy to develop a rotten world view if measures are not taken to handle that input.
A maximum limit of X months per year on the street or something, the other half in some other duty.
My take on the Floyd murder was there was definitely an element of a power complex that the cop devolved into over years.
I've worked in a consulting position with a German police union a long time ago (different than the US unions, they are regular trade unions here, generally left-of-center). The new guy running the local office told me that he was fortunate to discover exactly what you describe happening to himself and asked to be placed elsewhere so he won't start arresting every black person wearing baggy pants that he sees.
Police (no fault of their own) are woefully under trained given what is expected from them.
Of course, it will never happen because of the cost.