Don’t know if one of these 85 packages is the trouble maker
flatpak pkgs: 78 pm: snap pkgs: 7
But this one for shure
error: failed retrieving file 'custom.db' from disk : Couldn't open file /home/custompkgs/custom.db
Check your
/etc/pacman.conf
and garudafy it again, look for a line with custom.db and comment it out and run garuda-update again.
But be aware of the big KDE upgrade, prepare yourself by reading this KDE Upgrade Guide first