On Nobara, the Fedora repos are snapshots with certain packages filtered out that are manually re-synced roughly once a month.
This can result in Nobara's Fedora repo packages being out of date and occasional temporary RPM Fusion version conflicts (which also happen on Fedora, but due to RPM Fusion going out of date).
Do not worry, this is normal and all you have to do is wait for the repos to be synced again.
There are also some packages that are "missing" (filtered out) for compatibility or other reasons, such as fedora-workstation-repositories.
Nobara, as of version 41, does not have
plasma-workstation-x11or other X11 session packages in the Fedora repository snapshots due to no longer desiring to maintain or support X11 sessions. This means you cannot use deskrop environments with X11 sessions on Nobara like you can on Fedora.
Some X11 only desktop environments may be installable, but they are not supported and you most likely will not receive help with these. It is advised to choose another Linux distro if you require X11.
Unsupported desktop environments, window managers, or sessions relying on X11 packages include (note: Nobara only officially supports GNOME and KDE Plasma):
- KDE Plasma X11 (mentioned above)
- XFCE
- Cinnamon
- MATE
- Budgie
- LXDE
- i3