Microsoft has started replacing the legacy version of the Edge browser with the new Chromium-based Edge in Windows 10 Dev builds. The change is rolling out to all customers installing Windows 10 Insider Preview Build 21313, offered through the Dev Channel and available after joining the Windows 10 insider program. The Chromium based Edge browser was officially released in January 2020 with an installer that automatically replaces the browser on all devices. The new Edge is considered part of Windows 10’s overall security landscape and an integral part of the OS as Microsoft sources said.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-replaces-edge-legacy-in-latest-windows-10-dev-build/