I bought an iPhone 7 plus off eBay and I bought a rubber/plastic case I took the case off and then I saw scratches on the back of it?

I bought an iPhone 7 plus off eBay and I bought a rubber/plastic case I took the case off and then I saw scratches on the back of it?

And?
What is the problem?

I hope you got it at a fair price. It's a used phone.

It's possible that something very simple like some Sand or a little piece of rock any kind of particle could've gotten between the case in your phone and scratched it sort of like a car after you get your first scratch then you don't worry about it anymore don't worry about it life's too short