What is the most common reason why I would have dark half circles under my eyes at 26 years old? (photo)

I have smoked for around 5 years, I drink occasionally, workout almost everyday, and intake quite a bit of water most of the time. My father is gluten intolerant and I do have constant pressure on both sides of the top of my nose and above my top row of teeth. I use a coconut under eye cream before bed but I feel like it is more of a pigmentation thing.

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