Hey everyone
I recently switched to Fedora KDE 36, with Plasma 5.25.2. I'm using X11, because I'm experiencing bad visual glitches with Wayland (NVIDIA GPU).

Now I would like to enable some form of transparency+blur on Plasma's Breeze theme (dark). I have been searching for some time now, but I have not found a solution that is applicable/up-to-date.
Here's what I tried:

• Go to System Settings -> Appearance -> Application Style, click the Configure style button on Breeze, go to the Transparency tab and change it:
  
  That doesn't do anything.
• Look for transparent Breeze themes. I read somewhere that one "needs to use a theme that supports transparency". First result is always
  Breeze Transparent, but that's a Yakuake skin, right? Tried KvKonqi and Genome Dark with Kvantum. Not similar enough, and they don't respect the accent colour. They allow for some spotty transparency though (in Dolphin every other line is opaque...)
• Go to System Settings -> Window Management -> Window Rules -> Add New... and create a transparency rule for every window. That works, but it does not apply blur - even though in System Settings -> Workspace Behaviour -> Desktop Effects, "Blur" and "Background contrast" are enabled.
  There is also the "Translucency" option, and it allows me to make moving windows translucent, which works okay. They don't blur either, though.
• There is this Reddit post claiming that one can simply edit "/usr/share/plasma/desktoptheme/default/metadata.desktop" and change "contrast" to a higher value. This file does not exist on my machine, but I do have a "/usr/share/plasma/desktoptheme/F36/metadata.desktop" with the appropriate entry. Could not see any change from editing it though.

Does anybody know a working solution?

Note that panel transparency is working, and the one app that allows transparency while respecting the blur settings is `Konsole`.

Note 2: I asked essentially the same question on unix.stackexchange.com, and didn't get any replies or comments there. So I thought this might be the better place.