It seems like it’s been a conscious decision to have the text color in all themes reversed. Where 50 being the darkest, and 950 being the lightest.
As all the current themes and components appear to assume this will be the case for the text color when applying light and dark mode defaults, it might be to late to change.
This is more of a “I’m intrigued why they choose this pattern”, but does beg teh question, is this here to stay, or will there ever be a little button on the color ribbons in theme studio to reverse the ribbon? As currently the only way to create a text color that will play nice with all themes and components is to create a custom one (which is tedious).