As someone with astigmatism, I prefer dark modes in almost all places as long as it's done correctly. Bright screens with dark text cause significantly more eyestrain for me. My wife also has astigmatism and prefers light backgrounds with dark text. For the same reasons. I think the key here for accessibility is choice.
Environmental lighting conditions rule the day! I have astigmatism and I prefer bright backgrounds; #000 text on #fff backgrounds works great for me, but that's because I work in a room lit by a 250W 30,000 lumen corn-cob LED bulb[0] that makes my small office as bright on the inside as the shaded ground from a tree on an overcast day (which is quite bright compared to usual indoor lighting). In a room that bright, high contrast text works great and is highly readable, with "dark mode" often looking washed out and muddy. Even small reductions in contrast (such as what https://devdocs.io does with text of #333 in light mode) can make me notice and wish for greater contrast.
I too have astigmatism and am a light mode enjoyer. Dark mode makes the letters dance in front of my eyes.
Display brightness at 20% is life. Never made sense to me why you’d shine the light of a thousand suns in your eyes then put sunglasses on it because “it’s too bright” when you could just not.
My partner is a dark mode user and honestly sometimes her phone screen lights up the whole bedroom. Even with dark mode. I don’t understand.
I'm with your wife on this one, and also either one of those is way better than "grey on whatever" that seemed to be a prevalent design choice for a few years for many websites.
