WhatsApp offers a feature where you can create groups and add members for a more streamlined communication experience. Apart from letting users add members directly, one can also use the ‘Invite to Group via Link’ option. Our advice, you should completely avoid this.
According to a Lifehacker report, the "Invite to Group via Link" feature allows groups to be indexed by Google, which means they can easily be available online. By punching in the right keywords, one can easily enter private group chats thereby getting access to messages, phone numbers and so on.
Speaking to Motherboard, a WhatsApp spokesperson said, “Group admins in WhatsApp groups are able to invite any WhatsApp user to join that group by sharing a link that they have generated. Like all content that is shared in searchable, public channels, invite links that are posted publicly on the internet can be found by other WhatsApp users. Links that users wish to share privately with people they know and trust should not be posted on a publicly accessible website.”
In short, it is advised not to add members to your WhatsApp group using the link sharing feature. The reason for that is that once the link is generated and shared, it can end up on Google search and these group links are then available to almost anyone who is online. It is expected that WhatsApp will eventually prevent Google from crawling its website at some point, but until then it is better to save the contacts you want to add into the WhatsApp group and then add them directly.
If you have no option by to use use a link to invite people to your group, send the invites and once everyone has been added to your group, it is best to use your admin rights to reset the link. This way the previous link expires and the newly generated link is safe with you.