A fork of kickoff (found at https://invent.kde.org/plasma/plasma-desktop/-/tree/master/applets/kickoff) with one extra feature: the option of enabling submenus/subcategories.
Due to user complaints about the submenus in an older version of kickoff, the feature was removed, instead of making it possible to just disable/enable it (see: https://bugs.kde.org/show_bug.cgi?id=443742). This fork fixes that. Due to the way the feature is introduced, no changes in the layout were needed.
Kickoff website: https://userbase.kde.org/Plasma/Kickoff