Hey,
1. Why does `dnf group remove lxqt` wants to remove everything on my
system?
Most of it is not explicitely installed by me
https://paste.fedoraproject.org/291300/
That might be the reason. Dnf removes parts of the system that are marked as
"installed only as a dependency" as soon as the packages depending on them are
being removed. If you don't want this behavior, check out the config option
called clean_requirements_on_remove. You can also take a look at the dnf mark
command.
2. How can I reinstall lxqt group?
You first need to uninstall it. Groups are objects independent of the packages
they contain. Check out the dnf group mark command.
3. Is it a bug in dnf?
Doesn't seem like it.
4. Is there a reinstall option for group?
See my previous comment about dnf group mark remove.
HTH
Jan