I previously noted that ipp-usb was constantly running using (not too much) cpu time, but constantly cluttering up the running process list.
I finally decided to experiment and just did "dnf erase ipp-usb" which only removed that one rpm, then I rebooted (just to make sure).
I no longer have anything using significant cpu when the system should be idle, plus the USB printer (and the scanner) seem to still work fine.
In fact, the printer starts up immediately when I send it a page to print instead of delaying for several seconds like it did when ipp-usb was installed.
I fail to understand why ipp-usb exists.