The 72% number is the result when not controlling for demographics. When controlling for demographics, the results ranged from 65% to 71% accuracy.

https://www.nature.com/articles/s41598-020-79310-1/figures/2

It makes we wonder what the accuracy would be if they controlled for demographics at a smaller granularity, like sub-ethnicities.

Furthermore, it appears that the Canadian dating site data set was 54% conservative, so an algorithm that always guessed conservative would be correct 54% of the time. From the article I can't tell what the balance was for the other data sets.