In order to maintain ad serving on your content, you must ensure that your content complies with our programme policies. Some types of dynamic content are high risk (particularly user-generated content like forums). In these cases where we suspect risk, we may restrict ad serving until we've reviewed the content for compliance with our policies. These restrictions aren't considered policy violations unless Google determines that the content in question does in fact violate policies, and if that's the case, Google will issue a separate policy notification.
If you know your content to be non-policy violating, you can vouch for your content by letting us know that it's safe through requesting a review. However, please note that if we receive multiple requests for review that turn out to be actually policy violating, we may limit your ability to vouch for future cases of suspected risky content through review. For more information on requesting a review, see: Ad Manager, AdMob, AdSense.