I don’t know what you consider to be an advertisement but just off the top of my head:

Many (most?) streaming services advertise their own shows and other content ahead of other content you elect to watch even on ad free subs.

Hulu’s ad free subs have some shows that show unambiguous ads.

Prime and others muddy their interfaces with others’ “channels” and content that you can subscribe to through their service. They also show other content you can purchase or rent through them that aren’t part of your package. These things are included in search, viewing UI lists, and banner ads.