DIAGNOSIS That's hard water scale, and it means your dishwasher isn't getting enough detergent or the detergent isn't dissolving properly due to the wash water not being hot enough.
FIX First, run your kitchen faucet until the water is as hot as it gets. Then start a cycle. The dishwasher uses the incoming water temperature, so starting with hot water is crucial. Second, check your detergent. If you're using pods, make sure you're placing them in the main detergent cup and closing the lid firmly. For powder or gel, don't skimp—with hard water, you often need more than the standard fill line. Finally, make sure you're using a rinse aid. The KDTM404KPS has a rinse aid dispenser; fill it and set the dial to a medium setting (like 4). Rinse aid helps water sheet off dishes, preventing spots and helping to clear scale.
IF THAT DIDN'T WORK Your water might be exceptionally hard. You can try adding a small amount of citric acid (like Lemi Shine) to the detergent cup along with your regular detergent. This boosts the descaling power for a few cycles to see if it clears up.
HEADS UP Avoid using regular table salt in the rinse aid or detergent compartments. The dishwasher has a separate built-in water softener that uses special dishwasher salt, but this model doesn't have a user-accessible salt compartment, so managing hard water is mostly about detergent, temperature, and rinse aid.