This happens when certian news channels and government officials picture the BLM protests as all violent riots, lead by radical left wing people. Announce a BLM demo then and those people believing that get really afraid. And if you get any group of people afraid, some of them will respond with agression and violence on their own. That is just a law of human nature.

In Germany we have a criminal law term "Volksverhetzung" (Google gives "rabble-rousing") which you do if you put speech into public with just the aim to put hatred into some people against other people, with the danger that this confrontation gets violent.

Can get you up to three years in jail.