The caution on record is about relapse. DermNet lists IPL among the treatments that need expert use for melasma.
What DermNet says
DermNet says microneedling, intense pulsed light (IPL), and several types of laser carry a high risk for relapse and the disease becoming more resistant to treatment, so require expert use.
What that means for you
Relapse is the point to weigh, more than the first result. If you are considering IPL, ask the provider how they handle melasma in particular, and what they do if it returns.
Further reading
A laboratory paper looks at how intense pulsed light affects UV-induced pigmentation in human skin cells. For the condition itself, see the MedlinePlus melasma entry, the AAD melasma overview, and the DermNet melasma page.
If the patches return after a session
It changes if the patches come back after a session. Tell your provider right away, because DermNet links relapse to the disease becoming more resistant.