Microsoft Edge and Google Chrome are based on the same foundation ‘Chromium’ and development of core features are often shared between the two companies. Microsoft recently announced Windows Spellchecker support for Chromium platform and the feature is now live in all versions of Edge browser. Microsoft Edge Dev Build 84.0.522.5 for Windows and Mac comes with multiple improvements including support for Read Aloud feature in PDFs and full-page translation in Immersive Reader. Microsoft says it has also fixed an issue where certain types of videos like HEVC don’t play properly and another bug where webpages with videos sometimes hang.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-edge-gets-windows-spell-checker-and-other-improvements/