On Saturday, Google issued many manual actions (search engine result penalties) for "unnatural outbound links."
These penalties were issued by Google's manual actions team to sites that use outbound links as a way to manipulate search results.
It seems that Google is penalizing sites by not trusting any of their outbound links.
Webmasters received the below message:
If you see this message on the Manual Actions page, it means that Google has detected a pattern of unnatural artificial, deceptive, or manipulative outbound links. Buying links or participating in link schemes in order to manipulate PageRank is a violation of Google's Webmaster Guidelines.
As a result, Google has applied a manual spam action to the affected portions of your site. Actions that affect your whole site are listed under Site-wide matches. Actions that affect only part of your site and/or some incoming links to your site are listed under Partial matches.
To see if your site was penalized, log into Search Console and check your inbox for the above message. If you did get hit with the unnatural link penalty, you can find Google's instructions for fixing the issue here.