1. Duplicate content: Google penalizes websites that include multiple pages of the same content.

2. Thin content: Thin content is content that provides little to no value to the user, and Google penalizes websites that have too much of it.

3. Poor user experience: If your website isn’t easy to use, or if it’s slow to load, Google may penalize it.

4. Keyword stuffing: If you’re using too many keywords in your content, Google may penalize your website for keyword stuffing.

5. Link schemes: If your website is participating in a link scheme, Google may penalize it.

6. Malicious content: If your website contains malicious content, Google may penalize it.

7. Cloaking: Cloaking is a technique used to hide the true content of a website from search engines, and Google penalizes websites that do this.

8. Paid links: If your website is buying or selling links, Google may penalize it.

9. Unnatural links: If you’ve been building links to your website through unnatural means, Google may penalize it.

10. Hacked content: If your website has been hacked, Google may penalize it.