Hi, opening this but I'm studying yet the problem. It seems that after the upgrade of e2fsprogrs to release 1.47.0 this breaks the integration of grub when filesystem is ext4 and is created with that version.

I found some links about this issue:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1031325

What happens from my side on setup a new rootfs is this:

# grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=Macaroni_Linux --force 
Installing for x86_64-efi platform.
grub-install: error: unknown filesystem. 

The file system is not handled correctly.

Checking also Gentoo tree seems related to this patch:

https://github.com/gentoo/gentoo/blob/master/sys-boot/grub/files/grub-2.06-fs-ext2-ignore-checksum-seed.patch

So, i'm not sure if this patch works on grub-2.04 (available in prime) or it's better to move ahead to 2.06.

What I can confirm at the moment is that this issue doesn't happen when I use BTRFS instead. So, it's confirmed that is related to ext4 fs.

I will try to apply a patch and share feedback