Neither?

If your monitor is so bright that a white rectangle hurts your eyes, you need to turn it down.

On my current monitor I go from 100% brightness during the day to around 20% at night. I change it roughly twice a day.

I don't understand how, even with dark mode, someone could run a modern panel full tilt at 100% through the evening. My brain can sense the intense heat of that backlight behind every pixel. I don't even want the possibility of a momentary dark mode glitch to be a concern. It took me a long time to appreciate the harm of not controlling this stuff.