DIAGNOSIS That's mineral leaching or pitting. Hard water or acidic/salty foods (like beans cooked with salt added too early) can interact with the bare aluminum, causing a chemical reaction that leaves deposits or tiny surface pits.
FIX For cloudy spots, try cleaning with a paste of baking soda and water. Let it sit on the spots for 15 minutes, then scrub gently with a soft sponge. For more stubborn deposits, a 50/50 mix of white vinegar and water simmered in the pot for 10 minutes (without the lid!) can help dissolve them. Rinse extremely well afterwards.
IF THAT DIDN'T WORK The spots might be actual shallow pitting. This is mostly cosmetic and doesn't affect safety, but to prevent more, always ensure you're using enough liquid as a buffer and avoid cooking extremely acidic foods (like tomato sauce) or pre-salting beans in the bare aluminum pot for extended periods.
HEADS UP Don't use abrasive steel wool or harsh alkaline cleaners on the aluminum, as they can make the surface more reactive. The pitting can make the surface slightly rougher, so it may require a bit more scrubbing to clean in the future, but it won't cause the pot to fail.