This patch removes the login screen blur effect.
In addition to just the WallpaperFader, you'll also need to remove all the multi-state plumbing too: the mouseArea, the animated transitions, the uiVisible variable, etc. You'll also need to figure out a way to make the icon buttons and their white labels on the bottom edge of the screen not become illegible against white or very busy backgrounds.
You can see the approach I tried for these issues in D16031.
FWIW I originally used different separate patches to try various approaches for the bottom bar and the ActionButtons, but in the end I put them all into the same patch because they were an inseparable part of the remove-the-blur change and couldn't stand alone. You might want to consider doing the same thing here, or else you'll go through an endless nightmare of rebasing patches over and over again. :)
I can't believe I'm going to walk back my original argument from about a year ago but... yes it does, it makes it different but doesn't introduce inconsistency, at least not necessarily (because the design remains the same).
On the lock screen, the wallpaper fader serves a distinct purpose - to obscure the lock screen (clock + wallpaper) in order to make the user focus on password entry.
On the login screen, I'm not so sure - there's no lock screen to obscure, and the user login is the primary purpose, so all the wallpaper fader seems to do is obscure the wallpaper (which makes you wonder what's the point of having a wallpaper anyway?)
That being said, if you're intent on keeping the blur, I suggest tweaking the wallpaper fader (so the amount of blur/gray goes down). And in that case, I also suggest removing all the shadows except for the ones on (under?) the clock.
To do it the same way that patch did it in the end (Using sRGB textures) would require a Qt patch. That would magically fix all shaders. I've not tried, but it certainly looks feasible.
(Patch QSGMaterial to have a flag to push/pop GL_FRAMEBUFFER_SRGB) then patch QQuickOpenGlShaderEffect.cpp then add an option in QQuickShaderEffect)
We could copy and paste the FastBlur and square the fragment colours locally.
Sounds good! Way over my head but :D I like the idea of using sRGB in Qt as well.
P.S. It just occurred to me - if we kept the blur (and tweaked it a little) and used the same sddm background on the splash screen, we could get a "deblur as you unlock" effect.
Even better, if the user should decide to use the same background on the login screen, the splash screen and their desktop, the login could end up looking really nice and seamless.
I don't think this is applicable since the lock screen is already different from the login screen.
The objections driving this proposal are that the heavily darkened blur effect is kind of ugly, and that the wallpaper itself is indistinct and obscured, negating the entire purpose of putting a wallpaper there in the first place. That said, I kind of like @rooty's idea of keeping the blur but reducing its strength, and then un-blurring it on login and having the Breeze splash screen always show the un-blurred version of the wallpaper chosen for the SDDM theme. This would solve the problem of people being unable to see the wallpaper image, while preserving the legibility benefits of the blur.
If it's technically possible, this might be a compromise we can all agree on.