I think I found out how to do what you want. In the System Settings app, you will go to “Workspace Behaviour” (right under Appearance), then in the submenu choose “Desktop Effects”, and either scroll down (number 2 in “Appearance”) or search for “Blur”. To the right there’s a configure button that you press.
In the popup you can then configure the Blur Strength and I suggest you put it all the way to Light (to the left). Noise strength i have no idea what does lol.
Hope this helps, and if you need pictures I can do that as well
Edit: This will also change other places with blur.
And also remember to change the opacity settings of the panel (In edit mode, edit the panel, to the right “more options”, and then you can choose from there)