I have a couple of thoughts regarding this.

First, in America at least, we spend a significant amount of time and energy legitimizing "nonviolent, civil disobedience" actions of the past , while pointing at any group that defends itself in any other capacity as just as bad, or worse!, than the status quo/gov/cops/take your pic. There is only one valid way, outside the ballot box, to demand/make change within liberal society and it is to literally demand that the gov/cops/military/local assholes beat you so badly that other onlookers are too embarrassed to let it carry on. This method is lovely for the ruling class because they can physically squash the people with demands and, if they are few enough of them, the protest ends, and the ruling class get several more years to run things.

As an extension of above, protest organizers, and some protestors, explicitly know that the cops are there to escalate the situation. To avoid escalation many people simply do not defend themselves or others.

This is all vibes base analysis based on my own experiences at protests, including ones where cops escalate the situation. I wouldn't take it too seriously.