There's a significant percentage of brutal officers that for some reason aren't winnowed out in the hiring process--but that wouldn't be so bad if they were summarily dismissed when their actions betrayed them, and they usually aren't. Chauvin was said to have 18 citizen complaints on file. I'm a big proponent of unions, but not when they protect the guilty, as police unions often do.
I think the case that upsets me most is the Breonna Taylor case where police broke into her house while conducting a misguided and totally unnecessary raid, shot up the place and killed her--an EMT and aspiring nursing student--and wounded her partner. They had no idea the thugs invading their apartment weren't home invaders. But I guess they were, after all.