null!

I am receiving some infos from an API and I have to decerialize to a model
I am doing somthing like

if (response.IsSuccess) 
  //deserialize to Person
else 
  // deserialize to ProblemDetails

if (response.IsSuccess) 
  //deserialize to Person
else 
  // deserialize to ProblemDetails

And in person I hava defined properties using

public sting Name {get; set;} = null!

public sting Name {get; set;} = null!

Is the use of

 null!

 null!

here a bad pratice ?

null! - C#