The functios like as PyUnicode_FromString use a printf format in char array argument. Example: PyUnicode_FromString("a%22b"); in module interprete the %22 as 22 blank spaces. A double quote in module add a backslash. Poc:

Y try send a string from c++ to python string using:

PyObject* pyString = PyUnicode_FromString("/abc/def.html/a%22.php?abc=&def=%22;%00s%01");
....
PyObject* pyArgs = Py_BuildValue("(z)", pyString);
...
PyObject_CallObject(pFunc, pyArgs);

But in script the string is bad:

function(data):
    print(data)

The result is:

/abc/def.html/a              bogus %pp?abc=&def=                    %;(null)%