is attack on titan (shingeki no kyojin) episode 73 filler?

Mikasa Ackermann and Armin Arlelt sit with Gabi Braun at a table, who asks them why they protected her after she killed their comrade and bludgeoned a guard with a rock. Gabi asks for Falco Grice to be taken as a prisoner and for them to kill her.

Armin muses that her ideology reminds him of Eren Jaeger, who unexpectedly appears in the doorway. He silently raises his right hand, showing his palm has been sliced open and bleeding.