Independent connections for linked devices
WhatsApp's engineering team announced a limited public multi-device beta on July 14, 2021. The design supported a phone and up to four nonphone companion devices, each connecting independently. A linked computer could therefore continue functioning when the phone's battery was dead, rather than relying on a live connection through the phone.
The team described changes to encryption and synchronization that allowed message history and account state to be handled across devices. Independent connection did not mean messages became public or that someone could simply use another person's account without a linking process.
Source [1]The beta's scope and practical distinction
The announcement concerned an initial test with a small group, followed by broader rollout. It was not a promise that every device type or every feature was available to everyone on that day. Current linking controls should be checked in WhatsApp's own help instructions.
Leaving a group quietly is a separate privacy feature: it concerns who receives an exit notification, rather than which devices stay connected. The linked guide explains that distinction and why a quiet exit is not the same as an invisible one.
Source [1]