The only thing in my life that is not in dark mode are the hours of daylight, outside!!

Agreed.

I still however don't know what the difference between New Posts and Conversations tab is.

I have to scroll thru one and then scroll thru the other and I never know if I'm missing something in the time gap between scrolling between the one and the other.

I just need one screen that shows me latest posts and replies to get rid of this unsettlement.