When you got hit by the ender fireball by the ender dragon, the fireball will just give you a splash potion of instant damage and the weird maroon smoke particles, instead of the purple aura that hurt you

The wierd maroon smoke particles will not disappear or go away forever (also happened on lingering potion particles)

By the way, in the images, I decided to summon an ender fireball to test, and it still has the same bug

To remove unremovable particles, you have to set the time to night or quit the world multiple times