I feel this is a confusion from the multiple ways to do sets of people in M365. (And I also think it's compounded by not using Teams for day-to-day communication. In other places I worked with ...

The change marks the end of Office 365 E1, O365 E3, O365 E5, Microsoft 365 E3 and M365 E5 suites with Teams, the vendor previously said. For customers that want Microsoft productivity application ...