Apple restricts where advertising can appear — ads can't be injected into system UI, the Lock Screen, or notifications used purely as ad delivery, or otherwise pushed onto surfaces outside the app's own interface.
Usually caused by a monetization SDK that pushes ad content through local notifications or a widget as a way to reach users outside the app.
"Your app displays advertisements outside of your app's own user interface, per guideline 2.5.18."
Guideline 2.5.18 restricts where advertising can appear. Ads must stay inside the app's own interface and cannot be pushed to system surfaces such as the Lock Screen, widgets or notifications used purely for ad delivery. A monetisation SDK that reaches users outside the app is the usual cause.
System surfaces such as the Lock Screen, notification shade and widgets are the parts of the phone that belong to the user, not to any one app. If every app could place advertising there, those surfaces would quickly become unusable. The rule keeps advertising inside the boundaries of the app that earns from it, and it is also a consent matter, since users agreed to install an app, not to have promotions pushed into the rest of the operating system.
Yes, inside the app interface.
Promotional notifications are restricted and need consent.
They are allowed within limits and should not be deceptive.
Platform rules change often. This page is a plain-language explanation written by AppReviewFix, not official guidance. Check the current App Store Review Guidelines for the exact wording.