So yeah

  # curl ipinfo.io/34.66.115.47
  {
  "ip": "34.66.115.47",
  "hostname": "47.115.66.34.bc.googleusercontent.com",
  "city": "Council Bluffs",
  "region": "Iowa",
  "country": "US",
  "loc": "41.2619,-95.8608",
  "org": "AS396982 Google LLC",
  "postal": "51502",
  "timezone": "America/Chicago",
  "readme": "https://ipinfo.io/missingauth"}

What kind of url is that? This cant be someone using a browser as normal on their own machine can it? Could they be trying to build a google form or document or something that embeds part of the sign up form?

Edit: unsubstantiated source [0] says that domain relates to Google app engine, so could be the person is working on a project that includes some form submission capability and somehow is using your site for testing

https://superuser.com/questions/892437/what-do-you-do-if-you...