qubes-core-agent depends on -qrexec, there is no need for the opposite dependency. In fact one of the reasons for the package split was to allow installing just -qrexec package.
@@ -186,8 +186,6 @@ DNF plugin for Qubes specific post-installation actions:
%package qrexec
Summary: Qubes qrexec agent
-Requires: qubes-core-agent
-Requires: nautilus-python
Conflicts: qubes-core-vm < 4.0.0
%description qrexec