We experience the samme issue, running latest Outlook version in Semi-Annual Enterprise Channel, from August. (v2302 build 16130.20714)
Problem should be fixed in build 16130.20644, according to MS release notes.
But we only experience this issue when users are on VPN
When a user tries to access Outlook's To-Do app over VPN they will encounter the error message - and the issue does not go away until the user logs on via our central network, wipes the WEF-cache and restarts Outlook.
We have no issues when users are running Outlook / To-Do from non-VPN computers
So currently we suspect an issue with Microsofts Split-tunnel IP-list (or "Optimize Required")
Best regards
Martin