The bug

I tried to attack the ender dragon with a Sharpness sword with an impossible level of Sharpness, but due to MC-158205, she didn't take damage; however, it made enchantment particles (You will see these any time you have a successful attack with a Sharpness, Smite, or BoA item). I was baffled, so I tried with a Sharpness V sword and was able to reproduce it legitimately.

This can be reproduced in other instances as well, but this is the easiest way that I am aware of to reproduce it.

Steps to reproduce

With particles turned on all (might work with decreased also, I didn't test it)

1. Get a Sharpness item (doesn't matter the level, it can be a sword or an axe or any item really)
2. Attack the ender dragon with the sword
3. Wait for MC-158205 to occur (your attack fails due to the extremely buggy dragon hitbox)

-->  You will see enchanted weapon particles (teal particles)