Meshtags now require the geometry as second input
The decision of having to explicitly interpolate into a supported XDMF-file function space (will be a continuous lagrange space of same order as the mesh geometry) was made to highlight that this makes a loss of accuracy and can be an expensive operation.
If you are using higher order Lagrange/DG elements, you should use VTKFile or VTXWriter, as they support this kind of output. If you are using other spaces, such as RT, Nedelec etc, they should be interpolated into an appropriate DG space and use VTXWrtier or VTKFile for outputting.