Except OLED. It’s better for OLED to show white text on black background.
No because the white parts are what will burn in. Black is the off state for OLED. This is also why many apps for Lemmy (and previously reddit) have a dark theme option for OLED devices that uses full black instead of grey so that the pixels not in use are fully off.
Exactly, and because the rest is off you’ll notice it earlier. It still depends on how long those pixels are on though. The longer they’re on the more they degrade.
If the whole display is on all of the pixels would degrade eventually, but you’ll notice it less because they all degrade.
Every software needs a “just turn off the pixels that aren’t displaying anything” mode for OLED. Way too many “dark modes” are just dark grey which still keeps the background pixels powered.
Yes, because full black/white contrast is harsher on the eyes than a dark grey with white or light-grey text. For power/efficiency, black pixels definitely makes sense, but concerning user experience and eye strain, there are many good reasons certain color palettes are used.
Obviously not every single OLED panel can be tested for this if the manufacturers don’t do it themselves, but a few places tested OLED/AMOLED phones and found slate grey is close enough to full black in power savings. Since then I just choose the most visually pleasing theme as some full black themes are really poorly designed.