I found and fixed the problem. The key was in my systemd log.
1.825245] udevadm[363]: systemd-udev-settle.service is deprecated.
Please fix nm-initrd.service not to pull it in
Interesting; on my F34 system, the message mentions nm-run.service rather than nm-initrd.service. Neither nm-run nor nm-initrd exist as services, but something is calling systemd-udev-settle although it only takes 2 seconds to run and exit, so I never noticed this before.
--Greg