Google wallpaper... there is a setting that rotates the wallpaper every so often.
No I've checked everyone of them. None of them are turned on.
Yes that is the issue. At some point I was trying Microsoft launcher and Ven thoguh I made pixel launcher as default l, the MS launcher kept changing the wallpaper randomly. So I uninstalled it now and it appears to be OKIn that case, exactly which wallpaper are you attempting to use?
There are third-party wallpapers that do exactly what you are experiencing; possibly you installed one at some point in the past?