It’s a big one, and it’s anchored by Gravity Cages at the bottom. While these cages don’t directly affect anything else in the puzzle, I like to imagine they’ll combine to form a black hole, pulling everything in all four grids into a single cell.
When the arrow points to the bottom right, the cage is a Young Tableau, but something’s gone strange in this puzzle, and gravity seems to be pulling every which way. Some cages are upside-down or reversed or both, but the arrow always points in the direction of strongest gravitational attraction.
With the largest digit in the bottom right corner, these are also known as Young Tableaux. I’ve added an indicator arrow both as a reminder of the Young Tableaux constraint, and as a hint that future Gravity Cages might not always have the arrow point in that direction.