An over tightened sensor can leak also. There is a torque spec for sensors, tighten them too much and squish the O-ring seal and it will leak. Also could be a loose or damaged Schrader valve. They replace them when getting new tires and maybe didn't tighten one. Regarding the picture, I had a tire that looked very similar, I drove over a pipe sticking up in a parking lot. About 5 miles down the road the damaged sidewall let loose.