The decals have silvered badly. This is caused by air trapped beneath the decal and the flat finish paint. It's best to apply decals to gloss finishes, overcoat with clear, and finish with clear flat after you complete the weathering. You may be able to fix this, though. Apply some decal solvent (like Solvaset), and it may help the decals snuggle down into the paint. If any shiny bubbles remain, prick them with a pin, and reapply the solvent. Once dry, coat the whole area with clear flat, and it should resolve the problem.