Angel Wing Syndrome is a condition water birds can get along with other wing disfigurements. https://en.wikipedia.org/wiki/Angel_wing
The cause is believed to be an unhealthy diet such as people feeding them bread. It is probably what is going on with this coot. Please don't feed the birds "people food" If you want to feed the ducks, get some cracked corn from the bird seed aisle or at a feed store.
American Coot (Fulica Americana)