As the official WhatsApp site has just informed:
The multi-device beta is an opt-in program that gives you early access to try a new version of WhatsApp for Web, Desktop, and Portal. If you join the multi-device beta, you'll be able to use linked companion devices without the need to keep your phone connected.
This new multi-device option, when enabled for all users, can have a significant impact on ongoing integrations. Right now, we are investigating the possible implications and modernizing our integrations to make the future switching painless.
Do not update your WhatsApp mobile software and disable any automatic updates until the future notice we give you.