Hey, I have upgraded to F37 from F36 via GNOME software. My system though it was F36! DNF wanted to download F36 updates.
I have discovered that all F36 packages were still marked as installed in the RPM database. Fixing it was possible in the following way:
rpm -qa \*release\*
sudo dnf removeany
fedora-releasepackages still F36 - so that DNF would switch to F37 repos
sudo dnf distro-sync
This is very similar to this older issue!
Make sure to backup your system or make a BTRFS snapshot first.