When using a dispenser to launch a firework, it appears to change direction based on the angle you look at it from, similar to a particle, however it still moves the direction it was fired in. This is not the case when a player launches it normally or from a crossbow.

https://drive.google.com/file/d/1EzJSJ2T5d6LnOg2ZfmZNQ7JLLn4nmwOU/view?usp=sharing
Short clip with F3 menu because it is too large to upload here