Hi, I am planning to travel on the TGV 9577 from Karlsruhe to Stuttgart. I know that for TGVs reservations are normally needed, and this would be the case if I was coming from France with the train. However, the Rail Planner app is telling me that no reservation would be required. 

Is this true? Or is it better to just save the trouble and get a normal ICE train?

Thank you for all the help in advance :)