If God is an unchanging God, he is the same God in the OT as the NT. Just because he does some things differently does not mean he isn’t the same God. His attributes are all the same. God, in the OT, decided that all but 8 would die by flood. In the NT, God decides who will live with him in heaven, and who will go into hell. No different. It is God who decides according to HIS purpose, according to HIS will. Who are we, oh man, to tell the Lord of the Universe that he is wrong?
He is the same God; our perceptions are not.
Surely, you would agree that the ancient Hebrews ' perception of God was radically differet from the Apostolic witness of Christ walking, taling, helaing, and preaching among them.
What is attributed to God in the OT has a lot to do with the Hebrews' perception of what God outght to be like.
This human element is removed in the Gospels, because they are an eyewitness account (one way or another) of God's visible, audible and tangential presence among us, not a result of dreams, voices and possibly hallucinations of the OT authors.
Who are we, oh man, to tell the Lord of the Universe that he is wrong?
Who are we, o man, to tell us what God is like?