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/
If Google can update the user interface server-side, doesn’t that mean that disabling updates still wouldn’t work for avoiding these full screen ads?
depends on how they plan on implementing the update and what they already have in place software and firmware-wise