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/
Damn I considered one of these for a little bit when I was working on getting my own home streaming setup going. Decided against it because it looked kinda stupid and I hate Android and a lot of the stuff that comes with it. I guess I dodged a bullet on that one.
To be honest, there is hardly any good competition for the Shield TV Pro even on this day, but that is the fault of the industry completely.