1. Please describe the problem:

After an update to kernel-5.10.0-0.rc4.20201117git9c87c9f41245.79.fc34.x86_64 "root=LABEL=..." on a boot line no longer works.  A boot process is stuck searching for a root device by label with a corresponding udev task having no time limit.

Booting with "root=<explicit_device>" or "root=UUID=...." still works.

2. What is the Version-Release number of the kernel:
kernel-5.10.0-0.rc4.20201117git9c87c9f41245.79.fc34.x86_64

3. Did it work previously in Fedora? If so, what kernel version did the issue
   *first* appear?

This still worked with kernel-5.10.0-0.rc1.20201028gited8780e3f2ec.57.fc34 which happens to be the previous one I have installed.

4. Can you reproduce this issue? If so, please provide the steps to reproduce
   the issue below:

Yes, it happens every time.  The easiest way to reproduce is to modify accordingly "options " line in a corresponding /boot/loader/ entry
and try to boot.

5. Does this problem occur with the latest Rawhide kernel? 

This is the latest rawhide kernel I was getting.

6. Are you running any modules that not shipped with directly Fedora's kernel?:

no

7. Please attach the kernel logs.

There are no kernel logs from failed boots as / was not mounted.