How long have you changed your user information?
Please check that the user displays the correct information in the Microsoft 365 admin center.
Sign in to Microsoft 365 admin center> select the user with the problem > manage contact information.
If you just show the old name in Teams, this may be due to Teams' caching mechanism, which is designed to optimize performance and capacity. The Teams service caches general user information for up to three days, and the Teams client caches general user information locally for up to 28 days. Profile photos can be cached for up to 60 days.
For more details, you could refer to:
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