I unpacked decorations from storage and they’re coated in a strange white film. What happened?

may be best to dispose of the item to avoid health risks.
For items with minimal residue that can be easily cleaned, a little time and effort can restore their appearance. To prevent future issues, ensure your storage area is dry, well-ventilated, and free from extreme temperature fluctuations. With proper care, your decorations can continue to bring joy for years to come.