knockback -15647 enchant knock more then -10 knockback enchant.

I'm on a flat world. I started testing if there are bugs. Then i give myself a item with this command : give Minkizz minecraft:diamond_sword 1 0 {ench:[

{id:19,lvl:-15647}

]}. So i wanted to modify the give Minkizz -15647 enchant to -10. But -15647 enchant knock more then -10. Please fix this. I have a video but it's more then 10 Mo...
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