Are the police racist? You see articles that argue "no," like this by Heather MacDonald, and others that argue "yes," like this by Sherrilyn Ifill. For what it's worth, I'd argue they are not.
What police have a quite strong bias against is loud, belligerent, hostile behavior, particularly by young men, especially if those young men are "on" something - alcohol or drugs. Police are also prejudiced, by profession, against real or apparent criminal behavior.
If a particular demographic is more likely to be exhibiting those behaviors, it is likely to attract unwanted (and sometimes unwarranted) police attention, as we have noted in past posts.
As hammers seek out nails, so too do police seek out hoodlums, it is their job. If you are a law-abiding member of a troublesome demographic, expect unwanted and unwarranted police attention, keep both empty hands in plain sight, exercise care and make no sudden moves or stupid statements.