Office Insiders becomes Microsoft 365 Insiders - yawn
Office Insiders is now called Microsoft 365 Insiders but little else is changing for the Office app test program.
Since Microsoft is changing the name of almost everything to the “Microsoft 365” branding, it was inevitable that “Office Insiders” would be dropped in favor of “Microsoft 365 Insiders”.
For existing “Insiders” there’s no change. You’ll continue to get test versions of Office software in either “Beta” or “Preview” channels.
See Is it safe to join Office Insiders?
Insiders expands to more apps and services
Microsoft 365 Insiders is expanding its “purview” (Microsoft’s term).
That means future Insiders might include test versions of other Microsoft 365 apps and services such as Teams and Forms.
Learn.Microsoft.com
There’s a new sub-domain for Insiders release notes, among other things.
https://learn.microsoft.com/ is the new location for help with Microsoft products. It’s a rebadging of existing help and documentation under a new sub-domain.

Is it safe to join Office Insiders?