Windows Server 2022 adds support for Microsoft 365 Apps

We installed Server 2022 in August 2023, and out of the box we had onedrive sync and other 365 apps working well.
At the end of Oct 2023, work accounts vanished, and all Outlook, OneDrive, and Edge accounts refuse to log in or sync in app.
Users on the server can access web flavours of their account, or local word or excel apps - but everything else is totally borked.

This is a pretty barebones Server without much customization acting in a general shared file / storage role. But it has lost all ability to sync local files with OneDrive / SharePoint online which was the main goal.
It's bizarre that this was working - and then went away - while MS documents say "everything 365 should run just fine".