Microsoft has begun the rollout of its new Chromium-based Microsoft Edge to Windows 10 systems via Windows Update. This rollout is starting first with Windows 10 Insider in the ‘Release Preview’ ring. After a few weeks and if there are no problems, it will be delivered to all Windows 10 users. It is important to remember that when the new Microsoft Edge is installed it will remove Microsoft Edge Classic from Windows 10. Block Windows Update from installing Microsoft Edge automatically by setting a ‘DoNotUpdateToEdgeWithChromium’ Registry key to 1.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-rolls-out-the-new-edge-browser-to-windows-10-users/