Desktop app web viewer

As far as the desktop app's web viewer is concerned, this is the process that allows Outlook and many other Outlook apps to open and run. However, this recently had some performance issues and the Office team is now rolling out a new process called WebView2. This is currently rolling out to the production channel, at 50% of the current channel, and will be rolling out to the Enterprise Monthly channel on 04/14/2021.

If you open Outlook > click on File > Account Settings > you'll see if you're using the Production Channel, the Current Channel, or the Enterprise Monthly Channel.

You can also install the webview2 runtime here: Webview2 - Microsoft Edge Developer

This problem is likely to be present in any application that tries to publish from Outlook. Can you show a screenshot of the accreditation request? Are you using Exchange Online or on-premises Exchange?

Thanks,