Nobara has a dark desktop theme by default and I had to change it. It is annoying to me.
I understand that a dark theme looks cool and it does. However, it is less usable to me someone who wears glasses. Some people don’t wear glasses and find it fine. Great, You do you. It always surprises me why people argue about simple preferences and likes. Everyone is free to like whatever they want.
The reason that I share this is that by default OpenSuse had a light theme. I prefer that. It’s not a big deal to change the theme/desktop and it took about a minute but it is something to bear in mind if you are considering trying out Nobara.
Is there a downside to using a light theme? Perhaps you could incrementally use more energy by doing so, but it is so small that it is insignificant. It might let you focus better if you are doing graphics manipulation or video editing. I have seen professional designers have a grey background/desktop so that they minimize any impact that the color of their desktop has on their work. If you are in a calibrated desktop environment it might make a difference. None of those things apply to me, however, so that’s why I don’t mind getting a brighter desktop.
It is also practical for me. Since I have a huge projector/screen the light of the desktop is my main source of light in the room. It helps me to see generally when I have more light. So I prefer a brighter screen to a darker one. For example, when playing Cities Skyline yesterday it was a little darker than I wanted. The color wasn’t wrong. I just need to adjust it a little brighter. I tend to prefer a brighter screen when I play games as well. Shadows are overrated.