There could be any reason behind it and it's difficult to say. We usually go with the basic steps like sitemap, site structure, index tag, "Page available for index" on search console when manually checked, etc. If everything looks normal, then we can check for other factors like penalties and crawl budget issues.I revived a project after two years and rebuilt the site, but basically only the home URL is indexed—none of the others are getting indexed. Could this be related to the algorithm?
Thank you for the tip. It seems that a lot of people's websites were hit by this.Google wrote:
Google added on LinkedIn:
It's a global update and targets sites violating some of the Google search spam policies.
If you were hit by this, Google said you should review its spam policies to ensure they are complying with those. Google will do periodic refreshes to the spam update. It can take many months to recover, Google said.