The policy change focused on how messages and data would be handled when users communicate with a business in the ever-expanding array of WhatsApp Business offerings. Companies now could store their chats with users and use information about users for marketing purposes, including targeting them with ads on Facebook or Instagram.

Elon Musk tweeted “Use Signal,” and WhatsApp users rebelled. Facebook delayed for three months the requirement for users to approve the policy update. In the meantime, it struggled to convince users that the change would have no effect on the privacy protections for their personal communications, with a slightly modified version of its usual assurance: “WhatsApp cannot see your personal messages or hear your calls and neither can Facebook.” Just as when the company first bought WhatsApp years before, the message was the same: Trust us.

Additional reporting by Alex Mierjeski and Doris Burke.