Why are so many dark themes also high contrast? Dark mode is supposed to be easier on the eyes for people with healthy eyes. High contrast is not easy on the eyes. It's meant for those who do not have healthy eyes and hence can't see contrasts as well. For others it often looks like grid lines etc are especially shiny, making them really unpleasant to look at on a dark background. Pure black and white is bad enough but a lot of themes do even more, like LibreOffice, but also many websites.
#UI
@wildrikku Dark mode is also supposed to prevent eye damage resulting from longer screen times. Those who already have that type eye damage are often nearsighted and especially susceptible to lights in the dark. They suffer even more from high contrast in dark mode.