weired toolip in VS2019 C++

Question

I'm using VS Community 2019 C++ 16.9.2 on Windows 10 Prof. In a simple C++ project, I set Platform Toolset v142 and /std:c++17. Then in the .cpp, I include <string>, <vector> and "json/json.h" of JsonCpp.

Please take look at the screenshot

I explicitly use std to declare a variable of the vector of string, but the IDE shows me it's Json::Value::Members.

I'm not sure if it's a know bug or anything