Try blocking this domain manually and see if it works (it wasn’t part of my native lists in my router’s adblock)

androidtvwatsonfe-pa.googleapis.com    

If you have already set up your device and currently see ads, you need to reset the android tv home application data to get rid of them. This will temporarily show you the old dashboard, but the new one will load eventually (without ads, in its place it shows a dark “Google play, Youtube”, and something else that isnt very intrusive).