Dirt marks on back of phone

[SAMEELBHATTY]

I just noticed dirt marks/spots on the back of my Samsung A16. I tried rubbing them with a microfiber cloth and a glasses spray but they won't disappear, what should I do to get rid of them? 

[aakashnawab7]

Put a tissue paper in your pouch, use your phone for 1-2 months with pouch, these marks will vanish automatically.

[SAMEELBHATTY]

But I always keep my phone in a case and a protector