Maybe not in the UK, but this appears to be just categorically false in the US for example where officers who raise concerns about the behaviour of colleagues and unnecessary force are ostracised, moved to different precincts, thought of as a snitch instead of a hero working to make the force a better place, commit career suicide with no hope of promotion and the officers involved are routinely taken off the street, investigated, found to have done nothing wrong after bodycam footage shows them kicking a man to death or something equally bullshit and then reinstated.
I get that it's tiresome to hear the same old tropes thrown at you about your profession, but rather than deflecting and saying 'we're not all like this' which does nothing constructive than stop it being personally aimed at you which it never really was to begin with, it would be better if police said 'yes I agree with you all these people are terrible officers and we will all work tirelessly to eliminate them from our workplace' and took steps to do so.