https://www.qt.io/blog/qt-svg-not-so-1.2-tiny-any-more claimed that Qt 6.7 will support <filter> and <feGaussianBlur>. But it doesn't correctly render an SVG containing those elements in my case.

Attached are:

1. the source SVG file "alias.svg", extracted from the "Breeze" cursor theme in KDE;
2. test code "test.cpp";
3. PNG files rendered by Inkscape, ReSVG, and QtSVG in Qt6.6.2 and Qt6.7beta3

Both Inkscape and ReSVG render the SVG as expected. Qt 6.6 renders it without the blur effect. While Qt 6.7 renders a blank image.

test.cpp