EDIT:
So according to this thread, this is a Google related change and not Nvidia?
In which case, similar to the banner issue from a previous update, you can get a different launcher (see comments for FLauncher) to avoid it
https://www.reddit.com/r/ShieldAndroidTV/comments/181vh4t/ads_at_full_screen/
Get a dedicated streaming device like an Apple TV or Roku that can be swapped or upgraded independent of the TV.
Ironically, Nvidia shield is a dedicated streaking device that can be swapped. Don’t kid yourself, Roku is just as bad with the ads. They recently updated their UI to pack more apps into their home grid, so that they could show ads for other apps and shows. Recently mine says “continue watching” Supergirl in one of them constantly.
We’ve never watched Supergirl and don’t even have the app it’s on installed.