Microsoft announced support for concurrent Exchange Online license assignments, aka license stacking. This means that the workload can sort out the capabilities made available to a user through multiple licenses and make the maximum functionality available to the user through whatever’s deemed to be the “most superior” license. If that sounds like so much mumbo-jumbo, it might just be, unless you’ve been plagued by people losing access to their mailboxes because of shifting license assignments in the past. If you have, this change will make you very happy.
https://office365itpros.com/2023/01/25/exchange-online-license-stacking/
