Very strange. Have you tired pasting it in another client or in the browser extension?
Discussion
I haven't,
I'm afraid i may be logged out again and not able to use my nsec...
Is the nsec related to this user? Logging in somewhere else won't change your Amethyst login. You don't need to log off from amethyst to test.
What do you mean related,i tried to log in/out to see if i could do an update and it never let me logged in again, so i creates this new account on Amethyst,and i don't want to try on logging in/out on other clients as it may also do the same thing,lose my old account.
But have you tried logging in into other clients with your old account or just Amethyst?