Contradiction with Leviticus 27:30
It contradicts Numbers 18:18 by stipulating that all tithes of the land, whether seed or fruit, are holy unto the Lord and should be redeemed with an additional cost, potentially conflicting with the allocation described in Numbers.
Leviticus 27:30: And all the tithe of the land, [whether] of the seed of the land, [or] of the fruit of the tree, [is] the LORD'S: [it is] holy unto the LORD.
Contradiction with Deuteronomy 14:23
This verse suggests that Israelites should eat their tithe in the presence of the Lord, differing from the notion in Numbers 18:18 that the tithes, including the flesh of offerings, are given to the priests.
Deuteronomy 14:23: And thou shalt eat before the LORD thy God, in the place which he shall choose to place his name there, the tithe of thy corn, of thy wine, and of thine oil, and the firstlings of thy herds and of thy flocks; that thou mayest learn to fear the LORD thy God always.
Contradiction with Deuteronomy 26:12-13
These verses detail the distribution of the tithe every third year to certain groups, which focuses on charity, contrasting with the allocation to priests as stated in Numbers 18:18.
Deuteronomy 26:12-13: When thou hast made an end of tithing all the tithes of thine increase the third year, [which is] the year of tithing, and hast given [it] unto the Levite, the stranger, the fatherless, and the widow, that they may eat within thy gates, and be filled;