Having done a bit of looking around the web, it seems the most likely cause of the issue is still the appimagelauncher application. I realise that @MLXQt says they have removed it, but I would still like them to double-check that by running the following commands:
First, to check if any appimagelauncher package is installed:
pamac search -i appimagelauncher
That result should be blank. There are only 3 appimagelauncher packages available (all of them from the AUR): appimagelauncher, appimagelauncher-bin & appimagelauncher-git. If any of them are installed, they should be removed.
Then update the plocate database so that it won’t contain files which have been removed since the previous scheduled plocate update:
sudo updatedb
After that has finished, check if there is any version of AppImageLauncher which has been installed using another method. This will do a case-insensitive search for any filenames containing the string appimagelauncher:
locate -i appimagelauncher
Edit: Having just looked through the AppImageLauncher GitHub page, I saw that the AppImageLauncher command line tool is actually called ail-cli, so also do a search for that:
locate -i ail-cli
Once you are sure there are no versions of appimagelauncher on your system, reboot.
After logging back in, see if the shotcut appimage will now launch.