In order to maintain ad serving on your content, you must ensure that your content complies with AdSense Program policies. Some types of dynamic content are at high risk (particularly user-generated content like forums).
In these cases where AdSense suspects risk, AdSense may restrict ad serving until AdSense has reviewed the content for compliance with AdSense policies. These restrictions are not considered policy violations unless Google determines the content in question does in fact violate policies, and if that is 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 it is safe through requesting a review. However, please note that if AdSense receives multiple requests for review that turn out to be actually policy-violating, AdSense may limit your ability to vouch for future cases of suspected risky content through review.