How do people recognize an unpublished link to a google drive document?

Question

Google Drive

I observed more than once that after changing the rights to view a google drive document, several anonymous people immediately enter it. It looks something like this:

The permissions change to "Anyone with the link", which implies that anyone can get into the file, but only he has a link, but only I have this link at the time of publication. Question: where does the link come from so many anonymous people and who are they?

Answer 1

indexation corporation is good though )