But that's not who's protesting. The complaints are all coming from the left, primarily Black Lives Matters. Here's a report on the backlash. The backlash is mainly split into two complaints. The first is Pepsi co-opting protest culture to sell soft drinks. That's a valid complaint.
If anyone should be offended, it's Trump supporters. It makes protests seem cool, especially if Pepsi is involved.
The ad is sort of a feel-good version of the anti-Trump marches. People are carrying peace signs or signs that say "Join the conversation" and "love". There are a lot of minorities but the majority of the crowd is white. There are several cops present but none of them are visibly armed. A couple have riot helmets but most are simply standing there with their arms held behind them. There is no hint of violence.
The model picks up a can of Pepsi, gives a Pepsi-fist bump to a couple of people including cello-guy and has her picture taken by headscarf girl. Then she hands the can of Pepsi to a good-looking cop who is standing peacefully nearby. He drinks it and the crowd goes wild.
The add contrasts a big but friendly street protest and a professional model in the middle of a photo shoot. The model is wearing a slinky silver dress, makeup and a blond wig. There is also a guy playing a cello (or similar large stringed instrument) which is not part of the sound track and a woman in Islamic headscarf who is looking at contact sheets or something. The guy with the cello drinks a Pepsi and joins the march. The woman in the headscarf screams in frustration, scatters she contact sheets, grabs her camera and runs out the march. The cello guy catches the eye of the model who apparently is suddenly "woke". She pulls her wig off, flashes to herself with different makeup, then hands her wig to an older black woman and joins the parade. She also manages to change clothes in an instant.
The big story of the day (not counting poison gas in Syria and rocket tests in North Korea) is a "tone deaf" ad by Pepsi featuring Kendall Jenner.Assuming it hasn't been pulled, you can see it here.
The other complaint, and probably the real one, is that it makes the police look human. That's not how they put it but it's what they mean. It's a peaceful march, not a violent protest. The cops are engaged in traffic control. But the commenters keep going on about how a black marcher would be shot for approaching a cop like that.
Again, there is nothing in the ad to link it to the BLM marches. The closest anyone has come is a still of Kendal approaching the cop with a can and a picture of a BLM protestor being arrested.
But Black Lives Matters is all about teaching people that cops are terrible, people who will use any excuse to kill blacks. They still repeat the "Hands up, don't shoot" lie. So they can't allow an ad campaign that shows marchers and cops getting along. The ad has to go.