Probably one of the worst settling problems I’ve seen.
It looks like a brick veneer, and the problem may have come from the use of steel shelf angles buried below grade, which may have rusted out. If there isn’t similar distress on the inside of the house, the problem isn’t likely with the foundation, but with whatever supports the brick veneer. Was that side wall plumb inside, or a few inches out of plumb like the veneer is? Not sure where the pictures were taken, but it may be that the same thing is happening front and back. How about the floors inside? Did they take a dive in the same direction? If floors and inside walls are affected, then it probably is the foundation acting up.