Anecdotally, I very much doubt dark mode puts more strain on the eyes at night time.

During the day, I could see the "light mode" being preferable. But at night the brightness of devices seems quite damaging to eyesight and sleep.

If you have dim lighting, you can cause eye strain, and in extreme cases actual eye damage, by having small points of bright light in your vision like a phone or computer monitor because your pupils will be more relaxed.

Even now with the benefits of warmer color temperatures becoming mainstream knowledge, most people still use blindingly bright screens with high color temperatures, which causes more eye strain.

Also when you're staring at a monitor for 8-12 hours a day, it becomes less about readability and more about comfort. That's why most programmers prefer dark themes.

There's so many mixed signals and contradictory studies about eye strain and computer displays that I'm almost forced to conclude as a layman that it's totally subjective and up to the user. I've read about blogs and apps which go with a light design to reduce user strain due to being very text-centric, but then again there's studies that say programming benefits from a dark view for the exact same reason.

I've read about apps that switched from light to dark and saw a drop in engagement, but the same thing has happened for apps that go from dark to light, so perhaps it's just poor experimental control and the dip is just what happens to the user base whenever you change up the UI at all. There's always a backlash against that.

The studies are never very rigorous, either. There's also lots of persistent myths and misconceptions left over from yesteryear, such as the myth that being close to a CRT will actually damage your eyesight. I think that's conflated with dark-vs-light because of the typical retro image of a CRT displaying a green-on-black CLI. Seems that some people think reading strain means real eye damage, perhaps even permanent damage, instead of what it really means--quicker exhaustion and perhaps a headache.

The light UI has really won out completely in the wider world of consumer UI, while the dark UI is almost ubiquitous in certain niches and communities. People are always asking for or writing blog posts about the ultimate answer. I think it should just be up to the individual: what do you prefer? And UI design should move towards standards to support this user-based decision, offering both a light and dark mode that is easily toggled based on personal preferences and the ambient lighting where the UI currently exists.

This is 1980 in a time before OLED screens

Barely any computers have OLED screens.

If you prefer dark text on dimmed background try Dark Reader's light (dimmed) mode https://i.imgur.com/H38tpIS.png