The current obsession, internet-wide, with dark themes just doesn't make sense from a visual perspective. As with most current digital fads, it's all about PERCEIVED benefit - placebo - rather than hard facts based on research.
When one reads dark text on a light background, the predominant percentage of screen area emitting bright light, causes one's pupils to contract, therefore affording a deeper depth of field, and one struggles far less to focus on the text. I explained that poorly, suffice it to say that "dark mode" is just a fad UNLESS it's night time and you're sleepy, and the brightness of the screen is too painful to your eyes, in which case... TURN OFF AND GO TO SLEEP!!
Yeah, no. My eyes have been paining me all day for a while now, tried multiple eyedrops, nothing helped. I then switched everything to dark mode due to a friend's recommendation and now my eyes pain me way way less. I am not one to fall for placebo effects, I tried products made/imported by my father's company and was very quick to say that they are completely useless.
I am sitting in a brightly sun-lit garden as a type this. Upon seeing your reply I lowered my brightness and turned this add-on off (returned to the original theme), and at a brightness where the screen was legible my eyes started paining me in minutes...
Everyone is different. It is highly possible that a percentage of the population has some gene that makes them more sensitive to bright lights/screens. We dont have hard science, so we cant say dark mode is better, but we also cant say it is worse. I can only say that anecdotally it did help.