Microsoft has confirmed that today’s release of mandatory Patch Tuesday updates will automatically remove Edge Legacy and replace it with the new Chromium-based Edge. The new Microsoft Edge will be available as part of the Windows 10 cumulative monthly security update on April 13, 2021. Microsoft started pre-installing it on all devices that shipped with Windows 10 October 2020 Update. If you still use legacy Edge or you’ve blocked the Chromium Edge update using group policies/registry hacks, those settings will be ignored.
Source: https://www.bleepingcomputer.com/news/microsoft/rip-microsoft-edge-legacy-nuked-by-april-windows-updates/