Is it necessary to use a facial cleansing brush to wash your face?

Pigmentation on the legs can be due to a number of causes. Following eczema, the pigmentation is most likely post-inflammatory hyperpigmentation. This usually fades with time but may take weeks to months to clear. Some lightening creams may be prescribed to help this lighten faster. The benefits from laser for this condition though is less predictable. You did mention that your pigmentation has been there for years, so other causes of lower leg pigmentation including pigmented purpuric dermatosis, stasis dermatitis and lentigines should be considered.

It does look like a bit of hypopigmentation and you are correct that it is difficult to treat (most of the time we will have to rely on our own cells to re-pigmentate the area unless you explore other medical repigmentation options). I would suggest laying off the “gentler” laser treatment that you have every 2 weeks for the hypopigmented areas. That being said, the “stronger” laser treatment that you have every 6 weeks should be able to treat the Naevus of Ota (to avoid the hypopigmented areas). Usually, treatment of Naevus of Ota does not leave a white patch.