Where is the lock screen photo saved?

Hi,

the photo that I have in the Lock Screen is not in my photos, do you know if it saved somewhere and I can retrieve it? I’ve had the same photo for about 10 years!

For reasons I don’t know, a black line appeared on the Home Screen (only on the photo, not when I use apps). I wanted to replace it to see if it solves the problem, but I don’t want to lose the photo that I have in the Lock Screen.

I can’t find a way to only change the Home Screen background.

Attached the Lock Screen and the Home Screen.

I have an iPhone 8 with iOS 16.1.1

thank you!