Based on the pattern of the flaking, that started at the back edge of the bumper. This is very common for companies that use an oxygen or oxygen mix will cutting on a laser table since oxygen doesn't cut as clean as you might think. If that scale isn't removed before powder coating, your powder coat will begin to flake off pretty quickly. A small chick from a rock will then allow moisture to enter, and that'll cause the bubbling/flaking you're seeing today.
I would ask them if they cut with oxygen, oxygen/nitrogen mix, and pure nitrogen. Pure nitrogen will give you a clean edge, oxygen not clean, and the mix will be in the middle.
Mike