For the record, the current CentOS 8 Stream PXE init ram disk looks okay:
$ shasum initrd.img
$ lsinitrd initrd.img
Can you share your shasum? Can you try to delete the file and try again? There is a known bug in TFTP smart proxy - if a file gets replaced on the upstream site it simply appends the rest instead redownloading. This corrupts it. We need to fix this and now with CentOS 8 Stream which rebases the PXE images on a regular basis this should be our priority now.
It appears that the RHEL team tracks nightly build bugs as private, I don’t know why perhaps to prevent them from being indexed by google because it was reported on unfinished release. I guess things must be lined up because of CentOS Stream, I asked them about this.
Anyway, the referenced BZ is I think a different problem. I don’t see any kernel modules failed to be loaded there, that looks like some NetworkManager issue.
So I tested this on Foreman 2.3 running on CentOS 7.x (latest stable). I made sure that grub2 was updated to the latest EL7 version, I set up a libvirt VM EFI on an isolated network. And - downloading of initramdisk failed in all times with “Timeout error” leading to kernel panic.
I noticed something, the initramdisk has grown substationally over the last couple of years:
I wonder if this is simply a bug in grub2 EFI stack or in libvirt PXE stack, we have seen couple of them in the past. This can lead to timeout errors or corrupted init ramdisk which can then lead to very random errors (like the one you experience).
Now, I copied grubx64.efi from my Fedora 33 and then my VM immediately booted and provisioned just fine. Can you try that?