Install icons under icons/hicolor/scalable/apps instead of pixmaps
This is the recommendation of the Icon Theme Specification: https://standards.freedesktop.org/icon-theme-spec/icon-theme-spec-latest.html#install_icons
This is the recommendation of the Icon Theme Specification: https://standards.freedesktop.org/icon-theme-spec/icon-theme-spec-latest.html#install_icons