dark mode is easier on battery for OLEDs but not on LCDs where black needs the pixel to be fully active (white is off, black is on).

black on white is easier to read than white on black full stop, no astigmatism necessary.

ambient lightning is highly recommended to not strain your vision.

The link you shared literally says neither is better and it depends on the person.

	▲	baq 2 days ago \| parent [-]
		like "Also, in every color combination surveyed, the darker text on a lighter background was rated more readable than its inverse (e.g. blue text on white background ranked higher then white text on blue background)"? yes it's all preference, vision is subjective, but being surprised that dark mode isn't best is in this context... weird.