is one piece episode 858 filler?

In the Mirro-World, Luffy is intent on beating Katakuri, but Katakuri matches Gear 4 with his Chikara Mochi punches, and Luffy is once again unable to hit him at all. Katakuri binds Luffy with strands of mochi around his body, and assaults him with tendrils of mochi from the ground.

Luffy then finds himself overwhelmed as Katakuri creates several remote arms, and is unable to dodge Chikara Mochi for long as he is punched into the wall.