Microsoft Editor and native browser spellchecking are incompatible, conflict with each other
MS and Google collaborated on a new spell-checking engine, released on Edge version 83.
Microsoft Editor is butting heads with the browser's native spell checking - NOT AN EXTENSION - causing an unpleasant experience.
Even if both engines are set to the same language, red squiggles mark all words as unrecognized. Or words can have double red squiggles.
Disabling either engine would be bad.
The browser has a native spell-checker.
The user should not be forced to disable the native spell checker globally to be able to use Editor on OWA without conflicts.
OWA (and Word Online) should be able to override or disable the native spell-checker only on that site, without affecting the global browser native spell-checking settings.
The toggle controls to enable/disable orthography and grammar on the Editor settings should be used to switch between "Microsoft Editor" and "Browser Native" spell-checking.
I'm also having a terrible time with spellcheck in Outlook Web App. Lately it's started deciding that ALL my emails are written in Spanish (when obviously they are written in English), and every single word is squiggly underlined. I have tried changing setting the Microsoft Edito to English, the browser (Edge Chromium!) language setting to English, but Outlook stubbornly continues to underline every English word. I even tried setting the spellcheck to "All my languages", but still everything is underlined. Terrible experience, Microsoft! This started happening in the last few days (September 2020).