Those poll questions basically focus on one of three frameworks:
Patriotism. Trump said his objections to the protests were about “respect for our Country, Flag and National Anthem,” not about race.
Free speech. Some onlookers have defended the protests as a matter of free speech, regardless of what issues that speech is meant to highlight.
Race. When Colin Kaepernick first began protesting during the national anthem a little over a year ago, he said he wasn’t going to show pride in a country that oppresses people of color, citing a litany of police violence against black Americans.