You got the “Restricted ad serving” issue from AdMob.
The detailed information is “Site Behavior: Navigation”.
This issue happens to your Android app.
You need to fix it to remove your ad serving restriction.
1. Upgrade the AdMob SDK (Android) to the latest version.
2. Review all URLs in your application code to ensure that there is no broken link.
3. Upgrade all URLs with HTTP protocol to HTTPS protocol in your application code if there are any.
4. Repeat requesting a review in AdMob Policy center until it is approved. Typically it takes about a week for the restriction to be removed.
Include the below message in the review request.
We have fixed it.