dmesg | grep -i acpi | egrep -i 'warning|error'
Firmware Warning (ACPI): Optional FADT field Pm2ControlBlock has valid Length but zero Address: 0x0000000000000000/0x1 (20201113/tbfadt-796)
Firmware Error (ACPI): Could not resolve symbol [\134_SB.ALIB], AE_NOT_FOUND (20201113/psargs-503)
ACPI Error: Aborting method \134_SB.PCI0.VGA.ATC0 due to previous error (AE_NOT_FOUND) (20201113/psparse-689)
ACPI Error: Aborting method \134_SB.PCI0.VGA.ATCS due to previous error (AE_NOT_FOUND) (20201113/psparse-689)
This is on ufs
I don't know if this contributes to system freezes or other problems for more advanced settings and configurations.
Regarding the warning: Pm2ControlBlock being zero just means that this register block is not supported by the firmware. It's optional anyways.
Regarding the errors: The firmware is looking for a method called ALIB on the system bus (_SB). It is hard to find information about what this method does. Not sure if it is documented somewhere (surely not in the acpi specification).
A quick google search showed this github project, which sheds some light (not much).
Either way, I don't think FreeBSD can do anything about it (it's a firmware issue).