My understanding is that Fedora KDE preinstalls KGpg (through the @kde-pim group).

KGpg is effectively unmaintained. From my limited testing, it's quite rough and doesn't offer many of the features kleopatra has. (e.g., it doesn't allow creating elliptic-curve keys or adding subkeys), and doesn't use normal gpg components (e.g., doesn't use a pinentry for entering the pin for a new key). IMO its main view is confusing for non-expert users, showing certificates, subkeys, user ids and signatures in a single tree view. It also offers some questionable features (e.g., it lets the user create an address book entry for a subkey or a signature, whatever that means)

Kleopatra is actively maintained by upstream gnupg and doesn't have these problems.

(For transparency, I'm paid to work on kleopatra)