I have another idea, but consider that I'm not using your "gently" theme, and this stuff is theme dependent.
I never played around with transparency in the past.
With the standard "sweetified plasma" theme I think I managed to get to something similar to your expectations:
- Removing the "inactive blur" wallpaper plugin. As far as I know this can be done only manually removing a folder like mentioned here
- unflagging/deactivating Blur in the Desktop Effects
In addition to that, it might be necessary (again depending on what you have in your system) to find a suitable GTK Application style (in Appearence / Application Style) that foresees transparency. Tis is not the case for the standard "Sweet-Dark".