What bothers me when tithing is taught as a New Covenant necessity is that it puts people in the deceived position of believing they control their own blessing. This, and other teaching that tells the sons of God that if they don’t do the right thing, God won’t either, makes the complete sufficiency of Christ’s death and resurrection of little benefit (“in vain”; 2 Cor 6:1), other than a one-day home going to heaven.
The gospel loses its majesty, and the sons and daughters of God become like elder brothers of the prodigal, working in the fields to earn what they have already been given.
Jesus earned entirely everything for us for entirely nothing from us. In Him we have been given every blessing already. Believing that fact is the challenge; earning it is not.
Anything that teaches less than that makes us crazy.