Weird hitboxes following me on a specific world.

There is weird hitboxes following me but they arent entities /kill doesnt do anything they follow me, and where i look, i dont have any potion effects but the "thing" has a black potion effect it only happens on this world in creative where i am creating a map the map has stuff from old versions. Dont know how or when it happened, it looks like a area effect cloud hitbox and strange things whitout a hitbox.