Maybe it isn’t as private as you want your private Whatsap group. DW-journalist Jordan Wildon found that Google at least has been indexing some of the WhatsApp group searches, which allows users to sneak into groups that might not be open to the public. Although many are quite harmless, some contain sensitive information. Motherboard uncovered a Group seemingly targeting UN approved NGOs, where the list of all 48 members and their telephone numbers could be seen.
You won’t want to count on these invitations leaving the web, either. A WhatsApp spokesperson asserted these links were shared in “searchable, public channels,” and that people who want to keep links private shouldn’t share them on publicly reachable sites.
Google’s public search liaison, Danny Sullivan, reiterated this by saying it was “no different” than any other situation where sites allow links to be publicly listed. He added that Google offers tools to block content from being listed.