The prefdm script installed as part of initscripts calls `which' to determine which X display manager to run. If `which' is not installed then prefdm just exits with code 1, which causes it to be continually respawned. Either prefdm should not use which e.g., use type -path instead, or the initscripts RPM should have which as a dependency.
Thanks for the heads-up. This will be fixed in initscripts-4.93-2 and later in Raw Hide.