If you give a hostile mob such as a husk a weapon with an extremely high level of knockback, it will not knock you back extremely far (but it knocks them back the appropriate distance, which is always out of the world if they don't run into anything, if you hit them with the same exact weapon or they hit another mob with the same exact weapon) and a moment after you've been hit, you lose a great deal of hunger in an extremely short period of time.

Essentially, the player is for some reason not affected by the knockback effect above a certain level

Steps to reproduce:
1. Summon a husk holding any item with a high knockback level. Does not have to be 32767, can be much lower (I do not know the lower limit, if there is a clearly defined line, of this happening). I have tested it and found that level 3276 also works, and presumably everything in between.

Command to summon husk:

/summon husk ~ ~ ~ {HandItems:[{id:"minecraft:stick",Count:1b,tag:{display:{Name:"Whacking Stick",Lore:["Whack much far!"]},ench:[{id:19,lvl:32767}]}},{}]}

2. Make sure you have full hunger, go into survival, and get hit by it.