Google has long had a policy in place warning webmasters against unnatural/low-quality/keyword-rich widget links. In fact, the policy has been in place so long that it has become a fairly common SEO best practice.
So, why is it in the news again today? Google has taken it upon itself to reiterate the policy, specifically warning against “unnatural” links. Unnatural links are those that are built into a widget, and automatically placed on a site unbeknownst to the site owner. Often they contain keyword rich anchor text as well, and the worst part is site owners have no control over it.
Even though the site owner may be unaware they’re publishing links on their site in a black hat fashion, Google will still penalize the use of unnaturally placed links. Upon being hit with such a penalty, Google will notify site owners through Search Console.
Site owners may also receive warnings if links to their site are automatically included in widgets placed on other sites. If you have a widget out on the web that link back to your site, Google recommends fixing the problem and submitting a reconsideration request. The issue can be resolved by either removing the link(s), or adding nofollow attributes to them.
As an added precaution, Google recommends checking all widgets for any unnatural links. If possible, edit the widget to include a nofollow attribute, or remove the link altogether.