Ok, I solved this thanks to a reddit post I can’t link.
I had plasma-applications.menu in /etc/xdg/menus(which is what seems to be the new standard if I am not mistaken).
I tried running:
╭─ ~ 05:18:21
╰─❯ kbuildsycoca6
kbuildsycoca6 running...
"applications.menu" not found in QList("/etc/xdg/menus")
Which confirmed my suspicion that it was looking for the old file name for some reason.
This is where the solution comes from, just create a symlink and it should be fixed:
sudo ln -s /etc/xdg/menus/plasma-applications.menu /etc/xdg/menus/applications.menu
Hopefully this gets fixed soon so others don’t have to go through a similar thing.
Thanks.