GetSqlJson method missing from refs assembly

[MaceWindu]

Describe the bug

I'm testing new SqlJson functionality with SqlClient 6.0.1 and have strange issue with discoverability of GetSqlJson method on data reader

using var rd = cmd.ExecuteReader();
while (rd.Read())
{
        // CS1061: 'SqlDataReader' does not contain a definition for 'GetSqlJson' and no accessible extension method 'GetSqlJson' accepting a first argument of type 'SqlDataReader' could be found (are you missing a using directive or an assembly reference?)
	var value12 = rd.GetSqlJson(1);
        // even added assert to ensure it's expected type
	if (rd.GetType() == typeof(SqlDataReader))
	{
                // this works
		var value11 = ((dynamic)rd).GetSqlJson(1);
	}
}

To reproduce

Create new console project, add nuget reference <PackageReference Include="Microsoft.Data.SqlClient" Version="6.0.1" /> and try to access GetSqlJson method on SqlDataReader instance

SqlDataReader rd = default!;
rd.GetSqlJson(0);

Expected behavior

Code compiles

Further technical details

Microsoft.Data.SqlClient version: nuget v6.0.1
.NET target: (e.g. .NET Framework 4.7.2, .NET 6.0): net462, net8.0, net9.0 (tried all 3)
SQL Server version: Azure Database
Operating system: Win10

VS info

Microsoft Visual Studio Enterprise 2022
Version 17.12.4
VisualStudio.17.Release/17.12.4+35707.178
Microsoft .NET Framework
Version 4.8.09037

Installed Version: Enterprise

C# Tools   4.12.0-3.24631.1+da7c6c4257b2f661024b9a506773372a09023eee
C# components used in the IDE. Depending on your project type and settings, a different version of the compiler may be used.

[MaceWindu]

Actually found why it happens: refs assembly missing this method