Comment # 2 on bug 1177358 from Neil Rickert

I'm not sure why this is a bug report, instead of a forum post or a mailing
list inquiry.

VFAT is really just a layer on top of FAT that allows long file names.

Looking at what I have installed, I notice that "systemd-boot" uses as its efi
executable, the file "systemd-bootx64.efi".  And that long name would require
VFAT.  However, most systems use names that fit with the shorter 8.3 naming
system.

In my experience, the installer uses FAT32 (with VFAT).  At some time in the
past, it was using FAT16 for smaller EFI partitions.  But the current installer
is insisting on FAT32.  Most firmware seems to work with FAT16.  But I do
remember seeing one forum post where a user had to reformat his EFI partition
to FAT32 in order to get it to boot.  So some firmware is fussy about that, but
most firmware will accept either FAT16 or FAT32.