It can take longer to fade away. I don’t know what the treatments were like? I will say that I have worked on many, many women of Indian and Pakastani decent, using thermolysis, and some do develop hyperpigmentation and some don’t. It is the result of your skins particular response to injury - any injury.
I find that using cold aloe vera gel immediately after treatment is good for women of color. It calms down the skin and lessons the the skins over response to injury.