Contradiction with Numbers 23:19
This verse indicates that God does not lie or change His mind, contradicting any interpretation of Numbers 26:22 that suggests inconsistency in God's promises.
Numbers 23:19: God [is] not a man, that he should lie; neither the son of man, that he should repent: hath he said, and shall he not do [it]? or hath he spoken, and shall he not make it good?
Contradiction with Exodus 1:7
This verse mentions that the children of Israel were fruitful and increased abundantly, which might contradict a decrease in the number of individuals mentioned in Numbers 26:22.
Exodus 1:7: And the children of Israel were fruitful, and increased abundantly, and multiplied, and waxed exceeding mighty; and the land was filled with them.
Contradiction with Deuteronomy 1:10
The statement about the Lord multiplying the Israelites as the stars of heaven could seem contradictory if Numbers 26:22 implies a lesser count.
Deuteronomy 1:10: The LORD your God hath multiplied you, and, behold, ye [are] this day as the stars of heaven for multitude.