I have the same issue since yesterday. I don’t think I upgraded something, if I remember correctly I just added some new overlays and wanted to reboot the system to activate them. So maybe rpm-ostree did mess something up during the process.
Before the system reboots again, I get this for few milliseconds (I had to use the slow-mo mode of my phone to be able to record / read this):
error: ../../grub-core/fs/fshelp.c:257:file 'grub2/x86_64-efi/bli.mod' not found.
I tried to edit the grub.cfg / adding the bli.mod file manually, but no luck.
Tried to reconfigure grub from a live system, with no luck either: