is one piece episode 836 filler?

As Big Mom screams, she calls out to Mother Carmel and asks where she went to. A flashback starts, showing Big Mom’s past 63 years ago when she was five years old.

Linlin and her parents arrived at Elbaph's shore on a ship. Linlin’s parents tell her to stay on the island and promise Linlin that they will return and reward her with sweets if she waits for them.

Linlin replies that she will stay and wait for them and tells them goodbye as they leave Linlin alone on the island.