What others might like to do is what we have been doing for a few years.
I take a Screenshot of the Ethnicity results as soon as Ancestry says there is going to be an update.
Then I take another Screenshot just after the update.
All are filed as JPGs on my PC and backed up.
Comparing my Ethnicity from 5 years ago to what it shows now, one would presume it is the results for two different people.