The vt manual says this under the kern.vty heading,
Set this value to 'vt' or 'sc' to override the default driver used for the system console. BY default, sc(4) is used on computers that boot from BIOS, and vt is used on computers that boot from UEFI.
MY old DELL desktop boots from BIOS but yet I get vt graph mode auto selected.
According to the vt manual this should not happen. Tested on 11.0-ALPHA4.
The man page update is waiting on review and re@ approval: https://reviews.freebsd.org/D6901
Man pages were updated in r302055 https://svnweb.freebsd.org/changeset/base/302055