I think the best way to describe it is an absence of features that you would typically see in a period drama that align with the beauty standards of a given time. The ubiquity of cosmetic procedures is definitely part of it too because it has a tendency to make people look more interchangeable instead of unique, and the blatant tells of having had work done to their face would take you out of a film set in a certain era because it would be immediately noticeable. The artificiality and homogeneity negates the sense of timeless beauty πΏ