According to most Canon 6D II reviews, it has worse dynamic range than the original 6D or even crop sensor 80D. How is this possible?

Can someone who understands how sensors and other mechanics work , please explain how is it possible for a brand new camera to have worse dynamic range than older models?Does that mean the sensor in 6D II is not as good as in the original 6D? What about the crop sensor in 80D, many reviewers are sying the dynamic range is even better on 80D than 6D II.What did Canon do wrong with 6D II as far as the dynamic range goes? Thank you. via /r/photography http://ift.tt/2jiAoRR