In earlier versions of Yammer, when Yammer Enterprise was activated in the Microsoft 365 admin center, the Yammer tile was added to the Microsoft 365 app launcher for all users. When you looked at the Microsoft 365 Assign licenses page, you would see that Yammer licenses were disabled and couldn't be individually assigned to users.
Yammer licenses can now be modified at the user level, and the Microsoft 365 experience now reflects this functionality. For example, the Microsoft 365 app launcher shows the Yammer tile only for users who have a Yammer license. This resembles other Microsoft 365 services. Be aware that users can still log on from www.yammer.com by using their Microsoft 365 identities. For more information, see Manage Yammer user licenses in Microsoft 365.
For more information, see the following Microsoft websites: