Per the CDC, COVID is thought to spread "through respiratory droplets produced when an infected person coughs, sneezes or talks" and "between people who are in close contact with one another (within about 6 feet)." If a person is not coughing, sneezing or talking (like the guy in OP's pic) they don't even need to be wearing a mask, let alone covering their nose with it. And they certainly don't need to be wearing it, or wearing it properly, while more than six feet away from others.

These people snapping photos of someone across the street with their mask below their nose and crying about it are spreading misinformation and being overly cautious to the point of near-absurdity.

I'm all for proper precautions for COVID. But freaking out about someone doing nothing wrong is not helping anyone. Educate yourself, and relax.