The bug

For any /execute command where the rotation context is not first defined, the /execute as argument will inherit rotation from the target when it should not. /execute as should never be inheriting rotation.

Steps to reproduce:

• Create a new world with the Upcoming Creator Features experiment enabled (or use an existing world)
• Place down a repeating command block, enable the Always Active setting, and enter the following command into it. By principle this should make the particle emit three blocks south of the command block (x- and y-rotation values are 0).

  /execute as @p run particle minecraft:basic_flame_particle ^ ^ ^3
  

→ The particle's offset inherits the player's rotation and emits relative to the command block's position. The expected behavior is for the particle to emit southward, with x- and y-rotation values of 0.

• Now change the contents of the command block to be the following. This sets the rotation context manually.

  /execute rotated 0 0 as @p run particle minecraft:basic_flame_particle ^ ^ ^3
  

→ The particle emits three blocks towards south. Rotation is not altered by the as @p argument in this instance.