Hi @mshahabfar,
Thank you for reading my article 
and welcome to the Auth0 Community!
Sorry, I’m not sure I correctly understand your question. Are you saying that AddAuthenticationStateSerialization and AddAuthenticationStateDeserialization are not working as expected? 
Also, is your application using InteractiveAuto mode or Interactive WebAssembly mode?
If you can share some code, I can try to help.
To call an external API, I suggest using the approach shown in this article.