Google is currently testing a new “back to top” button in the mobile interface. The blue button with white text floats over the bottom portion of the search results as you scroll through them on your mobile device.
Sergey Alakov first spotted this while he was searching on his iPhone using the Chrome browser. The responsiveness of the button, according to Sergey, is poor and the user experience wasn’t great.
— Sergey Alakov (@sergey_alakov) November 4, 2016