Im using a samsung galaxy a20 and i see versions of the galaxy and samsung operating system without advertisments in various media pictures. Does this have something to do woth samsung customization service?
Samsung related apps that come with the phone post advertisements in the notification bar, when your start your phone, and maybe other place. So it's probably one of those app. This is samsung trying to market their new phones, I think your can disable them within the app itself that are posting it. Just check which app is sending you these advertisements.