This is education, not advice
The information here is written for the general reader and does not replace a personal medical consultation. It cannot tell you how your skin will respond to light, how many sessions you will need, or whether the mark you are concerned about should be treated with light at all.
No outcome is guaranteed
No light treatment can be guaranteed. How much pigment or redness changes, how long the change holds and how the skin settles afterwards vary between individuals, and a result is judged honestly only after the skin has had time to settle.
Pigment change and burns are real risks
Treated skin can be left darker or lighter than it was, and that change may fade only partly or not at all. Both broadband light and lasers can burn skin; a burn can blister and can leave a scar. Eye protection is required for the patient and for everyone in the room, because the light is bright enough to injure an eye.
The change is not lasting on its own
Pigment and redness recur. Sun exposure, hormonal change and the condition behind the redness all bring them back, so maintenance sessions and sun protection are part of the result rather than optional additions to it. Further treatment is usually needed to hold what a course achieved.