You received an app rejection from Apple on Guideline 2.3.6 and more specifically related to your app's declared aged rating. This article outlines why this usually happens and how you can solve it.
You received the following app rejection error from Apple:
2.3.6 Answer the age rating questions in App Store Connect honestly so that your app aligns properly with parental controls
You get this message the rating you have selected is inconsistent with the content of your app.
For example, you may have received the following note: Your app is rated as 4+ age but it allows filtered access to YouTube, where content with mature or suggestive themes can be accessed.
1. Log in to the App Store Connect
2. Change the age rating or disable the features that allow filtered access to content out of the age rating.
For more information, refer to Section Edit app age ratings of the Apple Set Up Ratings KB article.
Apple will review your app again and will probably not reject it due to the 2.3.6 guideline, as the request for age rating will have been properly justified. Thus, unless there's some other rejection reason, your iOS app will be approved and published on the Apple Store.