I recently moved to a 4k screen, coming from an ultrawide. On my ultrawide, the FOV was calculated correctly, according to a 21:9 aspect ratio. With the one i have now, it straight up... does not work.
It hapens with any option i set, and it happens with any game. tested with.. siege and dying light 2 and mass effect.
it really butchers games that have a sensitivity that is affected by FOV, too, since the FOV calculation is wildly wrong so is the sensitivity.