Good day!
I would like to change my nickname in minecraft. Unfortunately I cannot do this. The inscription "This profile name is not available" will appear on the nickname change page.
I am sure that my nickname is free, since when you enter any gibberish after it, it does not change this inscription.
At the insistence of the moment, my nickname is "_Wismut _". I want to change my nickname to "WismutNaN".
The site https://namemc.com/ also answers that the nickname is free.

Please help me with this problem.