Earlier you asked why someone would eat an animal found dead. If you think about it the answer is obvious.
A sheep or cow was a very valuable asset to its owner. Finding it dead would have been a significant loss. Obviously they would want to salvage something if possible. In Leviticus God said that whatever they decided to do it had to be included in the long list of normal things that resulted in uncleanness. Either burying or eating the remains had exactly the same consequences. I'm sure then the decision would largely be based on the condition of the carcass and how long it had been dead.
40 years later the circumstances of the nation were changing. Now they were going to be settling down in towns and villages and living among foreigners. Keen to encourage ceremonial cleanness Moses now encourages them to choose a better option of selling the carcass to a foreigner. That way - assuming the buyer collects - they don't have to touch or eat the carcass and avoid becoming unclean.
Nowhere in any scripture is the sacredness of blood mentioned in connection with eating an animal found already dead.
This is the anomaly you have still not attempted to explain.