Skin pigmentation treatment inquiry

Hello. I'd like to consult about skin pigmentation treatment because I've recently developed dark, uneven spots on my face and neck.

I'm concerned that brown marks remain where I previously had acne or other skin problems, and they seem to darken when exposed to sunlight. I've consistently used whitening cosmetics, but there hasn't been much change, so I think I need skin pigmentation treatment.

I searched the internet and found that there are various skin pigmentation treatments such as laser toning, pico laser, whitening injections, and taking tranexamic acid.

I'm curious about how each treatment works to lighten pigmentation, and which treatments are safe for my skin type (combination/sensitive). I'd also like to know more about the number of treatments, their intervals, the recovery period, and whether I can resume my daily routine after the procedure.

Additionally, I would appreciate it if you could also provide information on UV protection and lifestyle management to prevent re-pigmentation after the procedure.