My experience reflects OP's as well. It's not "ads", but things like searching using the SEARCH button inside a non-Apple app returns results from the Apple store.

If one uses it in a search box inside the app, it works in the local context. Imagine having to teach one's elderly parents what the difference is when the remote only has something like 5 buttons and one of them doesn't work how it's supposed to in a consistent manner. Local context vs. global context in searches is an absurd concept in the purview of the average consumer. Hell - I can't understand it half the time because it's so counterintuitive.

That's shady behavior and prioritizes Apple's own services over EVERY competitor.

Besides its terrible remote (the gen I have, at least), the usability constraints are insulting.

Roku has other severe limitations, but they don't outright manipulate their UI and their user experience in such an underhanded manner.

I'm confused by this too, and prefer Apple TV because it doesn't display ads. In my experience Roku does continue to display "special" ads, even if you turn off all user-controllable options.

I think parent commenters are referring to how the Apple TV app — which is great, but can be avoided by using the Home screen — aggregates all available content, and has a dedicated Apple TV+ tab. In other words, the Apple TV app is also the Apple TV+ app.