Depending on the water hardness, this occurs to a greater or lesser extent with all ultrasonic nebulisers. This is very fine limescale (dust), which then settles on everything, especially plant leaves and slightly "statically" charged metal or plastic (eg screen). Window panes are also a very popular target. With heat evaporators, limescale is much more likely to settle on the radiator, but bacteria are much more likely to multiply there in a warm environment. I therefore prefer "limescale cleaning".

Everything is fine with me