Change the Login Screen Wallpaper in Big Sur

ayamiharu wrote:

I love dark mode, and the new login screen wallpaper hurts my eyes. Too colorful, too bright! It used to be great in Catalina. How can I change this bright-colored wallpaper without doing a lot of codes or whatnot?

Thanks.

There is no user preferences readily available to make a change to the /System log-in.

You have to get past the pre boot...The preboot partition contains the code which handles the login for an encrypted drive, after that is successfully unlocked it is handed off to the main OS. It is here your user preferences are honored.

Apple Feedback http://www.apple.com/feedback

I posted a solution here: https://discussions.apple.com/thread/252056512

You're welcome, glad it worked!