Identify a pest before choosing a treatment. Household detergent and vinegar mixtures are not a universal remedy for leaves or roots.
Check what is actually present
A white mark can be dust, residue, a pest or damage. Examine the leaf surface and underside before spraying. Compare new and old leaves and record any recent change in watering, temperature or products used around the plant.
Avoid a universal spray recipe
Household detergent and vinegar mixtures are not a reliable treatment for every insect or leaf problem. Different plants can respond differently to contact with a spray. Do not treat an entire collection because one pot has an unidentified symptom.
Use plant-specific guidance
Once the problem is identified, choose an appropriate management method. If using a product, check that its label covers the plant, pest and growing setting. Recheck the plant afterward rather than combining several treatments at once.
Related reading: Small Insects Around Houseplant Pots: Start with Identification.