I explained to a police officer in my beer sharing circles during the George Floyd protests:

Damn near every kid in a high school cafeteria knows who the bad kids are and what tables they sit at. It's no different anywhere in the real world. Every cop at every precinct knows which cops are the bad ones.

Unlike a highschool cafeteria, you, as a police officer, have a civic, professional, and moral duty to do everything in your power to get those cops kicked the fuck out. And the idea that doing so might somehow harm your career? That's why "all cops are bastards." It's rotten from the top down. A few bad apples, in the case of police officers, spoils the whole bunch.