I'd say somewhere around 50% or more of Americans are pretty much understand that the cops have accumulated fairly unanswerable power, that something should be done about it and that nothing will be done about.
But another 30-40% of Americans believe cop movies/TV and think cops need to be able to shoot first and ask questions later 'cause of armies of "bad guys" armed with machine guns.
Look at the venn diagram between the first 50% and people who blow like grass in the political winds.
Unfortunately I will be surprised if a great many of the "reform the police" advocates stick around after it becomes apparent that "reducing police power" likely means some amount of "reducing the number of criminal infractions", "reducing staffing/resource allocations" and "reducing police's ability to screw people at their discretion" and that will greatly reduce their ability to call the cops and get a response to minor nuisance behavior. Unfortunately people really like using state violence as a cudgel against whatever they don't like.
I've been bitching about the cops for decades. Things have changed a lot since BLM came onto the scene and getting cops/government to generally treat people fairly and with dignity/respect after interactions have started (which seems to be the avenue where most progress is being made) would be a massive win but I see a lot of pitfalls that need to be avoided on the way there.
This is why BLM and the like generally ignore "reform the police" types entirely. Reform always ends up toothless for those exact reasons, so the only solution is to reduce their power in other ways (namely reduction of funds and repealing of criminal laws).
But another 30-40% of Americans believe cop movies/TV and think cops need to be able to shoot first and ask questions later 'cause of armies of "bad guys" armed with machine guns.