When working with Dynamic Type, I find it useful to remember that sizes for the different text styles won't scale linearly, nor will they do proportionally between them. For larger dynamic type sizes, styles will come closer together in size.

Graph showing how the text size changes, in points, for the different text styles, as the dynamic type size changes. It is noticeable how styles get closer and closer to each other as the user picks a larger dynamic text size. Tere is always a hierarchy, but for small sizes, it is much more distinguishible. It seems a good strategy though, larger styles are already quite large and smaller ones will benefit from growing even more in order to become readable on mobile deices.