Ur at the chronological time of Abraham was under control of Akkadians or Sumerians - depending of the actual time. About the same time it was then destroyed. 2,100-2,000 BCE
The Chaldeans were part of the NeoBabylonian empire 1,000 years later.
Therefore it could not be 'of the Chaldees'.
BUT if, as I am sure, the Hebrew Pentateuch was written by scribes around 700BCE, the scribes of the time would have thought of it in the terms of being where the Chaldeans of the recent NeoBabylonian had existed.
If 'Moses' had existed he would never have heard of the Chaldeans - centuries in the future.
The scribes wrote a history for the Jews while they were in exile. And they got their history wrong when they wrote their stories. 'Historical' novels, based around known places,