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.
Nonetheless, I think you should discuss your concerns with your treating doctor.
