Ok I think I have found the issue. Yes I have dark mode in android settings. But I am using Brave browser for android. I reinstalled using Chrome and it works with a dark splash screen. In Brave browser I used the Install App option, but it seems it is installed as a shortcut with a small brave browser icon on top of stacker news icon in the launcher. Although it does seem like a full screen app and all. In chrome is installed as an app without chrome overlay icon. Also I saw a cool lightning animation on chrome that I didn't see on Brave 😃