Soluction is :

QgsVectorFileWriter.writeAsVectorFormat(layer,
"/Users/user/Desktop/gis/Excel/NUTS_ID_AT111978Q1.csv",
"utf-8",driverName = "CSV" , layerOptions = ['GEOMETRY=AS_XYZ'])

using r".." in lunix was part of the error are this is a shortcut for windows path formatting.

The second mistake was passing none as a projection. Specifying the drivename as it is a keyword argument as the layer option seemed to have solved it.

Solution is :

QgsVectorFileWriter.writeAsVectorFormat(layer,
"/Users/user/Desktop/gis/Excel/NUTS_ID_AT111978Q1.csv",
"utf-8",driverName = "CSV" , layerOptions = ['GEOMETRY=AS_XYZ'])

using r".." in linux was part of the error are this is a shortcut for windows path formatting.

The second mistake was passing none as a projection. Specifying the drivename as it is a keyword argument as the layer option seemed to have solved it.

Soluction is :

QgsVectorFileWriter.writeAsVectorFormat(layer, "/Users/user/Desktop/gis/Excel/NUTS_ID_AT111978Q1.csv", "utf-8",driverName = "CSV" , layerOptions = ['GEOMETRY=AS_XYZ'])

using r".." in lunix was part of the error are this is a shortcut for windows path formatting.

The second mistake was passing none as a projection. Specifying the drivename as it is a keyword argument as the layer option seemed to have solved it.

Soluction is :

QgsVectorFileWriter.writeAsVectorFormat(layer,
"/Users/user/Desktop/gis/Excel/NUTS_ID_AT111978Q1.csv",
"utf-8",driverName = "CSV" , layerOptions = ['GEOMETRY=AS_XYZ'])

using r".." in lunix was part of the error are this is a shortcut for windows path formatting.

The second mistake was passing none as a projection. Specifying the drivename as it is a keyword argument as the layer option seemed to have solved it.