It's certainly true that some of the institutions that are being talked about for being pushed to take up some of the slack when we defund the police do not have the best records, either. My family has had harrowing experiences with the mental health system, so I am absolutely cognizant of the genuine concerns with trying to increase their role.
But that means that we should also fix the problems with those institutions, not that we should just allow the police to continue to operate with impunity, no matter their abuses.
It may be a long, hard road, but ultimately I believe we can have a safer, kinder, more just society as a result.