In more detail
Google enforces its spam policies in two ways: automated systems and manual review. When a reviewer finds a violation, Google can apply a manual action. Its Manual Actions report help page lists the types, which include:
- Unnatural links to your site, or from your site
- Thin content with little or no added value
- Cloaking and sneaky redirects
- Pure spam and user-generated spam
- Structured data issues
- Hidden text and keyword stuffing
- Site reputation abuse
Each manual action in Search Console explains what was found, which pages are affected and, often, examples. Fixing the problem means removing or correcting what breaks the policy, such as removing paid links, rewriting thin pages or fixing markup, then submitting a reconsideration request that explains what you did. Google reviews the request and either lifts the action or explains what remains.
Manual actions are different from ranking changes caused by algorithm updates. A core update isn't a penalty and doesn't appear in the Manual Actions report.
Why it matters when hiring an agency
Manual actions are usually the result of tactics like buying links or mass-producing thin content, sometimes carried out by a previous agency. Google is clear that site owners are responsible for the actions of companies they hire.
If you suspect a problem, check the Manual Actions report in Search Console before assuming anything. If you need help recovering, ask agencies about their experience with reconsideration requests, how they'll audit links and content, and how long they expect it to take. Avoid anyone who promises a quick removal; Google decides, and reviews can take time.