I had this happening to me as well.
Normally after an update to the package grub, I do:
grub-install --no-nvram
and
grub-mkconfig -o /boot/grub/grub.cfg
But today after reboot, I had the same issue as yours.
I tried then again with:
sudo grub-install --efi-directory=/boot/efi
and this resolved the issue for me. Looks like, this time, the EFI entry needs a renewal.
I thought it was an issue on my end.
If other users are also hit by this, perhaps an “announcement” should be made on the forum.
Edit:
correction: --efi >> --efi-directory.
Thanks to @gipo355 for bringing it to my attention.