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/
Do you have the playstore on it?
On the TV? Yes, I do.
I haven’t tried using adb to install new launchers yet.
Try this one
https://play.google.com/store/apps/details?id=com.spocky.projengmenu&hl=de&gl=US
Been using it for a year now, really happy with it.
Is it easy to set up as the default launcher?