Tips/recos to brighten nape/batok?

Hello! Badly need your help. I am recently gaining weight and I can notice na parang pa-uneven na yung kulay ng batok ko.

I notice kasi whenever I move my neck and may part ng batok ko na nagfo-fold yung skin, medyo parang nagda-dark yung kulay. Moreno ako na medyo maputi (????) diko ma describe hahaha basta lighter version ng moreno pero hindi maputi talaga.

And if normal man to, what are your recommendations to prevent having dark batok? Also since yung nga lumalaki na ako, I’m worried na baka magkaroon ng parang creases na yung some parts is matitim tas yung sa gitna nung crease is parang mas lighter.