It’s not that you won’t have any knowledge in the day of completeness, but partial knowledge is insignificant in the light of the fullness of knowledge.
Even after you’re born again, you can only see as if looking in the mirror in the dark. (see 1 Corinthians 13:12)
God gives you a promise. Even though you now have faulty vision, you will know as you are known. (see 1 Corinthians 13:9-12)
As God knows you, you will know God and reality.