Why is there a difference between dark mode and black background mode?

Why are the new words marked differently in dark mode vs black background?
When I click on a word in black background mode it’s barely readable because it turns black and the new words are also harder to spot because the blue colour opacity is way to high, thus fading into the background.
Why is this even any different at all to the dark mode theme where you have perfectly readable words that don’t change colour when I click on them as well as seeable new words with a higher contrast to the background?

Why is it changed now, why to the worse blue? I mean thanks for deleting the word turning black when clicking on it but I think the other blue was definitely better.