Inkscape offers some nice filter effects to create svgs, e.g. frozen glass. But none of these filter effects is visible in KDE applications (dolphin preview, in icon themes). Applications not using ksvg can display the filters and effects so it is not an inkscape-only thingy. It would be great if KDE applications also could show the filter effects, would be great for creating svg icons and svg wallpapers. Reproducible: Always
Neither icons, nor the wallpapers use KSVG2. It is probably only used in KHTML. If you want better SVG support in icons or wallpapers, they would need to switch to QWebEngine, because that's the only Qt SVG renderer, that supports SVG filters.
Oh, sorry, I don't know the internal structure... If ksvg only is used in khtml - for which internal part icon/wallpaper rendering should be reported as they obviously use the same engine?
Wallpapers: either "plasmashell/Image Wallpaper", or upstream to Qt if the wallpapers are loaded by QImageReader. icons: either "frameworks-kiconthemes" if applications use KIcon, or upstream to Qt if applications use QIcon. Plasma may have its own icon (QML) classes. QtSvg is limited to https://www.w3.org/TR/SVGTiny12/ and I am not sure if QtWebEngine has API to allow rendering SVG without instantiating a full web browser. For small icons, the overhead is probably insane.
Hello! Sorry to be the bearer of bad news, but this project has been unmaintained for many years so I am closing this bug.