Yes. It's obnoxious.

On my parent's it doesnt render anything at all. Just shows the wallpaper.

I think it hides the big ad area if it can't get the data, but I haven't used my Roku outside of the setup in so long I don't know what the UI would look like.

I've done this on VIDAA (Hisense) and there's a placeholder for the homescreen ads that just say "VIDAA".

In some cases. There is a blank square on the main menu. The idle screen also normally had an ad. The idle screen looks like a scrolling cartoon panoramic shot of a street, and the ad is a billboard on the side of the street. That billboard simply isn’t there at all if the ad is blocked.