mount: unknown filesystem type ‘vfat’

The vfat kernel module isn’t getting loaded. Possibly because of the CIS benchmarks. This can be a problem for EFI systems (mounting /boot/efi isn’t possible without vfat).

Somewhere in (on RHEL based systems) /etc/modprobe.d vfat is getting blocked. Look for a line like: install vfat /bin/true in one of the files. Replace that line with just vfat and all should be well.