is bleach: thousand-year blood war (bleach: sennen kessen-hen) episode 6 filler?

While reading Sōken Ishida's journal on a riverbank in Karakura Town, Uryū Ishida notices two pages stuck together and pulls them apart to reveal information on a Quincy extermination performed 1,000 years ago, to his surprise and confusion. Questioning if this is related to the extermination from 200 years ago as well, Uryū sees a drawing of a younger Captain-Commander Genryūsai Shigekuni Yamamoto and wonders what it is meant to signify.

Meanwhile, in the Seireitei, Yamamoto stands before Yhwach, who grins at him while holding an unconscious 11th Division Captain Kenpachi Zaraki up by the throat.