The black dots you're seeing are most likely thrips droppings. These tiny insects puncture the leaf surface to drain sap, resulting in silvery streaks, mottled patches, curling and eventual leaf drop. They thrive in warm, dry conditions and are easily introduced when plants are moved outdoors. Once inside, they spread rapidly, particularly on mature, leafy specimens. Their damage is often mistaken for nutrient deficiencies or sun scorch, but the telltale sign is the combination of silvery streaks with tiny black specks.