How to fix dark theme and not hurt my eyes?

Dark theme lacks continuity and hurts my eyes
I have set the browser to dark theme on both my desktop and mobile device. Any time I load a new webpage, the screen first loads a white screen that is very suddenly replaced with the webpage. It would be easier on eyes if the background screen prior to loading were compatible with the dark theme.

How can this issue be reproduced?
Any time I load a new webpage on mobile or desktop Brave.

Expected result:
I’d like a dark background set before webpage loading so there is no white screen flashing.

Brave Version( check About Brave):
desktop - Version 1.0.0 Chromium: 78.0.3904.97 (Official Build) (64-bit)
ios - Version 1.13 (19.11.06.18)