That's a physiological issue that occurs when your plant takes up water from the soil with dissolved minerals (salts) in it. Some of that water, with salt dissolved in it, makes it to the surface of the leaf. When the water evaporates, it leaves behind the salt it contains as a little white powdery dot. This is also harmless, but could be a signal that the level of dissolved solids (salts) in the soil is creeping upward. If you witness it, you might try flushing the soil thoroughly - especially if you've been watering in small sips so the plant doesn't have to deal with soil saturation. That particular way of watering ensures that all salts from your tapwater and fertilizer solutions remain in the soil where they can create quite a bit of mischief. The salt deposits on the leaves will rub right off with a damp cloth or paper towel.

If the dots don't wipe off, suspect another physiological issue called oedema.

Oedema

Oedema is a physiological disorder that can affect
all plants. It occurs when the plant takes up more water than it can
rid itself of via the process of transpiration. The word itself means
'swelling', which is usually the first symptom, and comes in the form
of pale blisters or water-filled bumps on foliage. Under a variety of
circumstances/cultural conditions, a plant's internal water pressure
(turgidity) can become so high that some leaf cells rupture and leak
their contents into inter-cellular spaces in leaf tissue, creating
wet or weepy areas. Symptoms vary by plant, but as the malady
progresses, areas of the leaf turn yellow, brown, brown with reddish
overtones or even black, with older damage appearing as corky/ scaly/
ridged patches, or wart/gall-like bumpy growth. Symptoms are seen
more frequently in plants that are fleshy, are usually more
pronounced on the underside of leaves, and older/lower leaves are
more likely to be affected than younger/upper leaves.

Oedema is most common in houseplants during the
winter/early spring months, is driven primarily by excessive water
retention in the soil, and can be intensified via several additional
cultural influences. Cool temperatures, high humidity levels, low
light conditions, or partial defoliation can individually or
collectively act to intensify the problem, as can anything else that
slows transpiration. Nutritional deficiencies of Ca and Mg are also
known contributors to the malady.

Some things that can help you prevent oedema:

* Increase light levels and temperature

* Monitor water needs carefully – avoid
over-watering. I'd heartily recommend a soil with drainage so sharp
(fast) that when you to water to beyond the saturation point you
needn't worry about prolonged periods of soil saturation wrecking
root health/function. Your soil choice should be a key that unlocks
the solutions to many potential problems.

* Avoid misting or getting water on foliage. It
slows transpiration and increases turgidity.

* Water as soon as you get up in the AM. When
stomata close in preparation for the dark cycle, turgidity builds. If
you water early in the day, it gives the plant an opportunity to
remove (for its own needs) some of the excess water in the soil.

* Put a fan in the room or otherwise increase air
flow/circulation. Avoid over-crowding your plants.

Al

So informative! Thanks 😊

Thanks and a belated thanks for the kind words.

Al