I added these lines to remove the accounts used by room and shared mailboxes (the script also needs a Connect-ExchangeOnline command).

# The accounts used for Room and shared mailboxes can hold licenses (for example, for Teams Rooms Devices or to get a larger quota for a shared mailbox)
# so we remove these accounts here
$OriginalUserAccounts = $Users.Count
Write-Host “Finding Azure AD accounts used for shared and room mailboxes…”
[array]$NonUserAccounts = Get-ExoMailbox -RecipientTypeDetails SharedMailbox, RoomMailbox -ResultSize Unlimited | Select-Object UserPrincipalName, ExternalDirectoryObjectId
Write-Host “Removing non-user accounts from set to be processed…”
$Users = $Users | Where-Object {$_.Id -notin $NonUserAccounts.ExternalDirectoryObjectId}
$RemovedAccounts = $OriginalUserAccounts – $Users.Count
Write-Host (“Proceeding to process {0} user accounts after removing {1} room and shared mailbox accounts” -f $Users.Count, $RemovedAccounts)

“managers are not real humans”? Gosh, that’s a big statement to make…

The point about Teams rooms devices and licensing is true. https://office365itpros.com/2023/03/29/teams-rooms-devices-licenses/

I shall think about how to filter those room mailboxes out…

Well, it may filter out most of them. Microsoft Teams Rooms license (currently in Basic, Pro, and Premium flavors) is assigned to room mailboxes when you have in-room meeting hardware. There may also be service accounts with subscriptions that have a manager listed. As always, YMMV but this is a great starting point. Thanks Tony.