Search Engine Optimization (SEO) is not as simple as clicking a button; it involves multiple moving parts to be effective. In spite of the positive effects that SEO can offer to your site (when done correctly), there are a number of factors that can negatively affect your Google rankings, such as:
1) Your site is not mobile friendly,
2) Your site has bad redirects,
3) Copyright Violations
Read more here: https://bit.ly/3rA1t39