"On March 30, 2020, Microsoft announced that the consumer plans of Office 365 would be rebranded as "Microsoft 365" (a brand also used by Microsoft for an enterprise subscription bundle of Windows, Office 365, and security services) on April 21, 2020, succeeding existing consumer plans of Office 365."
So M365 is actually more correct then 0365.
I asked a colleague, who is managing M365 licenses at MS and he agrees with your statement Adrian that M365 is more correct than O365. What he also mentioned that the case is a bit more complicated and in practice both, i.e. O365 and M365 are fine to use.
