My wife has had a work iPad with Outlook (Classic) on it, and the entire app locked up pretty much in-line with the reported outages. No ability to scroll, no ability to open previously-downloaded eMail, no ability to access on-device settings, nothing. It’s like the app itself had encountered an internal error that turned it into a glorified wallpaper screenshot.
Such lack of responsiveness doesn’t line up very well with what I know as a software dev, nor with my own experiences with apps that are no longer connecting with services. Although TBH I have never developed for mobile before. Maybe I’m missing something?