Reflect ghast fireball with a empty hand.
Hold a sword enchanted with knockback in main hand, repeat an action in 1.
Related issues
Attachments
Comments

[media]

Can confirm.
Can confirm. A fireball reflected using the knockback enchantment will travel no faster than a fireball reflected without the enchantment.
Here is a command to help reproduce this issue by summoning a stationary fireball:
/summon fireball ~ ~1 ~

Can confirm in 1.20.5rc2. Knockback no longer propels fireballs faster. This might be intended?

Can confirm in 25w18a.