You can make a camera over-expose but I have never heard of anything like this.
I would first assume it was the camera not taking a good picture over it being the tank.
Possibly a derivative of this: http/www.wired.com/2009/09/russian-billionaire-installs-anti-photo-shield-on-giant-yacht/
Don't know that a tank would be worth the cost, though. I'd imagine it's not cheap, and there's not really much information that needs a photo to convey, at least for military purposes.