I changed my minecraft username, but i don't think it got updated and I am not able to play on servers now(My xbox gamertag and minecraft username are different)

I changed my minecraft username, but i don't think it got updated

Websites such as namemc are not official, but they can be useful for such purposes. check there. If it hasn't changed, try changing it again? If you still can't, please contact mojang support.

I am not able to play on servers now

How can you not? It would be great if you could add an error message or screenshot

Thank you for your report!
However, this issue is Invalid.

Your game, launcher or server is modified.
If you can reproduce the issue in a vanilla environment, please recreate the issue.

• Any non-standard client/server/launcher build needs to be taken up with the appropriate team, not Mojang.

• Any plugin issues need to be addressed to the creator of the plugin or resource pack.

• If you have problems on large servers, such as The Hive and Hypixel, please contact them first as they run modified server software.

Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki

Thank you! The issue has been resolved on the vanilla client