sub claim name changes

[Akronae]

I'm signing a token this way

var claims = new ClaimsIdentity(new[] { new Claim(JwtRegisteredClaimNames.Sub, sub) });
var tokenDescriptor = new SecurityTokenDescriptor
{
    Subject = claims,
    Expires = DateTime.UtcNow.AddDays(5),
    Issuer = Issuer,
    Audience = Audience,
    SigningCredentials = new SigningCredentials(
        new SymmetricSecurityKey(Encoding.UTF8.GetBytes(Secret)),
        SecurityAlgorithms.HmacSha512Signature
    )
};
var tokenHandler = new JwtSecurityTokenHandler();
var token = tokenHandler.CreateToken(tokenDescriptor);
var jwtToken = tokenHandler.WriteToken(token);

So I'm creating a claim with name sub and value xxx

However when a request is made using a token, the only claim I can find is name http://schemas.xmlsoap.org/ws/2005/05/identity/claims/nameidentifier and value xxx
(From System.Security.Claims.ClaimsPrincipal.Claims ControllerBase.User.Claims in my ASP controller)

The value is still the same but the claim name is not sub, though it is when I check the signed token.
Why is that ? How can I access the Sub claim without hardcoding this "url" claim name which seems unreliable?

Using Microsoft.AspNetCore.Authentication.JwtBearer 7.0.9