Google is testing a new banner style call to action within their hotel knowledge panel on the mobile search results.  When searching a hotel that has sponsored room rate listings, Google is showing a new floating banner on the bottom of the page with a link to view rates.

Sergey Alakov made a GIF showing it in action:

The banner links to the rates page.

He also notes that Google is also testing a different color variation as well:

This test is pretty notable since Google is using an overlay style directly in their search results, even though it is for an advertising product, as this has never been a method they have used for promotion in the search results.  But it definitely raises the questions if Google could use this in other areas of the search results as well, or for further calls to action within a knowledge panel.