Try trouble shooting this.
Swap lenses on the same body and see if that still shows. Then try the 70-200 on a different body, if you have access to another one. That will hopefully give you an idea if the problem is with the body or the lens. I honestly can't even guess what it might be, but it looks like a smear on the lens, maybe the back element?
Also try changing apertures and see if that affects it in any way