I recently got a CPO iPhone 11 from the Koodo site.  The problem is that my wallpaper keeps disappearing and I am left with a black background.  The phone still works properly, and all of my apps are there.

I have tried shutting off power, turning it back on. and my wallpaper comes back.  A few minutes later the background just turns black again while I am using the phone.  I performed the most recent software upgrade too.

Any suggestions?