When launched by a Dispenser Firework rockets do not go sideways, even if I dispensers facing horizontal

The wiki is not always accurate. This has never been a feature.

Ok.But they need to make It possible to launch sideways.Because 18w43c is a experimental snapshot.

Despite the wiki being incorrect about this, it'd be interesting to see dispensers fire fireworks in the direction they're facing in order to match the behavior of crossbows and fireworks.

This was a feature exclusive to Bedrock Edition, but it has now been ported over and will be in Java Edition 1.15 as well.