Hi Jason,
There could be a bunch of possibilities, depending on your initial pigmentary issue. Most often lasering of pigmentation with any laser can potentially cause a post-inflammatory hyperigmentary (PIH) darkening of the area.
This can happen if slightly stronger or incorrect settings are used, or if you are just more prone to PIH formation (which most asians are).
As such, careful and gradual approaches should be sought in pigmentation management in Asians. Picosecond lasers tend to work best for pigmentation, with the least possible risk of PIH formation. Feel free to contact my clinic should you need more advice on the issue.
Best Regards,
Dr Shane Abucewicz Tan