Google gave plenty of warning to owners of sites with “sneaky” mobile redirects; which is anything that misleads the user into visiting something they didn’t intend to. Now Google is taking action against those who did not heed the warning when they had the chance.
As announced on Google+, the Google Webmaster Team has been delivering manual penalties to these sites. If your site has been affected, which you could tell by a significant decrease in organic search traffic, then the company invites you to visit this help center article.
The article explains the process you have to go through to clean up your site, submit a reconsideration request, and hopefully have the penalty removed. Let this be a warning to other sites guilty of sneaky mobile redirects; clean up your sites now!
Google first added the use of sneaky mobile redirects to its Webmaster Guidelines back in April 2014. Today marks the first time the company has publicly announced mass manual actions as a result of sneaky mobile redirects.