is one piece episode 867 filler?

Luffy continues fighting Katakuri in the Mirro-World, and Katakuri's sister Flampe looks on as she prepares to shoot Luffy with her blowgun. Luffy keeps attempting to strengthen his Observation Haki and foresee Katakuri's attacks, and although he is not on Katakuri's level yet and continues getting pummeled as a result, he is developing it very rapidly.

Katakuri recognizes this, and as he realizes he needs to finish Luffy off quickly, Flampe successfully shoots Luffy in the leg with a blowdart.