The protests are widespread for a few reasons.
1) Black poverty is widespread. Apparently centuries of repression couldn't be resolved in just a few decades. Some people like to blame blacks for the crime and violence (generalized, not about the protests)... and yes, there is no excuse for crime and violence... it is an indicator of poverty, not race. Much like how blacks die from cancers more often than whites or that blacks are dying more often from COVID-19 than whites. People think blacks are more susceptible to COVID-19 as well as committing crime? No... it's the poverty.
2) Systemic bias is widespread. While there is racism, I think that systemic bias is the much bigger problem, ie playing the odds. Some black guy trying to force his way into a nice home... must be a robber, not a professor at Harvard. Or these nice white guys say the black guy lunged at them, and him being black and them being white, this is a viable explanation from people that'd go to prison if they admitted to reckless actions that caused a death.
3) No one is listening... is widespread. We've seen the videos of evidence being planted, officers needlessly shooting, etc... This stuff has been alleged for a while. And this particular case, the officer had lots of complaints against him... but no one listened to those complaining, and because of that, someone is dead. People are tired of being ignored across the country. And the culture in the Police needs adjusting.
Exactly !! Socioeconomic status is the variable, not race !
"ItS SoCiOEcOnOmIc!!"
Socioeconomic factors in cities fairly tightly correlate with race.
Humans are infamously known for conflating correlation with causation, and using bad "proxies" that are easy to discern in lieu of harder-to-observe underlying causes (you can
see when someone is black; you cannot see when someone is poor.). This is the very definition of prejudice and racism.
You can't honestly expect any rational, critically thinking person to buy, given the knowledge of this historically consistent effect, that the effect just magically disappeared from the human psyche.
In fact it has been studied many times and when people in various occupations making decisions on what homes to show or what products to offer, or even asked whether the person they saw is a criminal, even when controlling for socioeconomic factors, sometimes when people are directly aware of socioeconomic factors at the outset, direct black people to lesser "more affordable" options, away from "white neighborhoods", towards shittier products, or impugn them as criminals.
It's almost like when you have such campaigns as "around blacks, never relax", people wil take that to heart no matter how fucking racist that is.
And as it stands, studies indicate that actual criminal acts are committed at roughly equal rates per capital. The correlation people draw mirrors the imbalance in enforcement by cops. It's not that black people commit more crimes, but cops have historically enforced more vigorously against the black community, because the previous generation of cops arrested more black people... And so on, due to momentum carried all the way back to the days of race based slavery.