When you're doing group commands, you don't use the "@". That's only
for package management commands to distinguish it from a package name.
So what you mean to say is that when I am installing a group via dnf install the @ is required but when I am using dnf group install @ is not required since dnf already knows its a group.
Am I correct ?
"LibreOffice" and "libreoffice" are equivalent. The latter is the short
form which makes more sense with other groups, particularly ones with
spaces.
Yes but this still does not explain why LibreOffice does not have its own DNF Group (except for the one that does not work) .