Twilight Sparkle

Confirmed in Java Edition 26.2.

This issue now also affects the new minecraft:apply_impulse entity effect. The effect interprets its direction vector using the affected entity's local coordinates, so when it is applied to an arrow with:

{
  "type": "minecraft:apply_impulse",
  "direction": [0.0, 0.0, 1.0],
  "coordinate_scale": [1.0, 1.0, 1.0],
  "magnitude": 2.0
}

the impulse is applied in the opposite direction on the world X and Y axes, while the Z axis is correct.

For example, a fully charged arrow with an initial velocity component of approximately 3 is reduced to approximately 1 along X or Y instead of increasing to approximately 5.

When fired diagonally at approximately 45 degrees in the XZ plane, the measured Motion components were approximately:

X = 0.70
Z = 3.47

This matches the expected result if the X component of the impulse is negated.

Using:

"coordinate_scale": [-1.0, -1.0, 1.0]

correctly compensates for the inverted projectile rotation and makes the impulse follow the arrow's actual movement direction.

This means the issue no longer only affects visual rotation and local coordinates (^ ^ ^); it can now directly alter projectile velocity and trajectory through minecraft:apply_impulse.