Phantoms have the pitch inverted compared to the rotation value. This messes up commands using local coordinates.
Steps to reproduce:
Run the following command in a repeating command block:
execute at @p positioned ^ ^ ^5 as @e[type=phantom] run teleport @s ~ ~ ~ ~ ~
observe the phantom's facing direction
Expected result:
The phantom has the same facing direction as you.
Actual result:
The phantom faced up when you face down, and vice versa.
This report is an edited copy of the java edition equivalent: MC-134707.
Can confirm