Remove blur effect on lock-screen

I have a slideshow running on my desktop (which is stored in ~/.local/share/shotwell/wallpaper/wallpaper.xml) and which also is shown in the lock screen.

Since 20.04, there is a blur effect on the current image in the lock-screen.

I only found solutions how to use another image on the lock-screen without blur, but that would remove the slideshow.

How do I remove the blur but keep the slideshow?

There is a Extension called Control Blur Effect on Lock Screen..

Control Blur Effect - Gnome Shell Extension

By default the Settings of the Extension make the Blur Sigma Value to 0, This means you can see the wallpaper without any Blur Effect.

Optionally you can Control this value and Brightness value too from the Extension Settings..

In relation to the bounty and reference to unlockDialog.js not found on system:

The reason why you cant find unlockDialog.js on your system is that is the source code that seems to be compiled by gjs.

What you are asking for is part of a complicated procedure. The way I would look at dealing with this is to download the source code to make the required changes.

1. Edit the apt sources to add a source for ubuntu source packages
2. Install gnome-shell source. (apt source gnome-shell)
3. Change into the gnome-shell directory
   cd /usr/share/gnome-shell/
4. Edit the files /usr/share/data/org.gnome.shell.gschema.xml.in and /usr/share/js/ui/unlockDialog.js
5. Add a changelog entry (file /usr/share/debian/changelog) to update the version to higher than what was installed from Ubuntu
6. Install the build dependancies. These are packages installed and used just to build the package gnome-shell (sudo apt-get build-dep gnome-shell)
7. Run debuild command to build a package. (Installed via devscripts package)
8. There should be a .deb file in the parent directory of wherever the gnome-shell directory is.