Hi @Tonito Dux
To better understand the scenario, would you please share some more information on the issue?
1.What are the initials before the change, and what are the expected initials after the change?
If possible please give an example.
(Don't forget to hide the personal information)
2.Does this user have a middle name?
3.Are you seeing the initials change in Microsoft 365 admin center?
If yes but in Teams it doesn't change, it may possibly be caused by Teams server cache.
Reference: User information isn't updated in Microsoft Teams
Please wait some time for the information to be updated.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.