Google is testing a new icon in the mobile search results that symbolize when a search result links to a page that is not mobile friendly. The icon is a mobile smartphone with a slash through the phone. Here is a picture from @malcolmcoles:
This is compared to what Google was testing a couple weeks ago with a mobile friendly icon in the mobile Google search results. That looked like this:
Google is clearly testing to see if they see a better response from searchers either from showing a mobile friendly icon, a non-mobile friendly icon or no icon at all.