it tried to add usdt from available asset, but it’s always on loading
How do I submit a bug report? (Official Brave Help Center article)
https://support.brave.com/hc/en-us/articles/360018228951-How-do-I-submit-a-bug-report-
Example of a good report:
How to stop the settings cog wheel icon from disappearing in Brave?
Such organized reports, help Brave Support to more carefully and quickly determine how to proceed.