The reason behind this is WhatsApp’s “Click to Chat” feature that creates links and QR codes. While the feature helps in easily letting others get in touch with you through WhatsApp, it exposes your phone number to the public. Click to Chat is designed to let others connect with you without sharing the phone number or having them on a contact list. The convenient feature designed for business communication makes your phone number publicly searchable on Google.
There has been constant debate over whether this is intentional or bug. Google Search algorithm pulls the phone number from Click to Chat link’s metadata, which is then saved to Google Search Index.
The problem is that many WhatsApp users are unaware of this. Many people try to keep their personal phone number private but using this feature it ends up on the internet. Researchers have offered several suggestions to keep WhatsApp phone number out of Google’s every result. However, none of these suggestions has been implemented by WhatsApp’s dev team.
The only way to keep your phone number off Google’s search index is by not using the Click to Chat feature. If you have already used Click to Chat, delete any links that you may have created. If you want to continue using Click to Chat without compromising phone number, consider using a service like Google Voice with WhatsApp.