What is the cause of this discoloration & how can I treat it? It looks I have freckles as if the skin is darker. (photo)

I have got this skin discoloration about 2 months ago. They are mainly on my forearms.I need to know if there's any possibility this could be something malignant. They are not scaly they are flat and not itchy. They seem to look brighter in sunlight. Im also getting like small rounded flat brown spots. What could this be i am female 28 years old

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