Possibly...but I'd look for another answer, like a change in food source (recently harvested crops etc) first. Coyotes are really only a threat to young fawns in spring. Although it is possible, especially when in a pack, it's not that easy for a coyote to catch and kill a full grown deer. Even in winter in the deep snow there needs to be some fairly specific snow conditions and circumstances for coyotes to be a serious threat to adult deer.

could they pressure them enough to keep them nocturnal or is it me?

Coyotes are active at night too so if the deer suddenly went nocturnal that probably means they've figured out that they're being hunted by a 2 legged predator that doesn't come out at night.

It may not even be you that tipped them off - small game/waterfowl/muzzleoader/archery hunters, combined with the changing seasons definitely serve as indicators to any deer which survived last hunting season that rifle season is just around the corner. They may be onto you or (hopefully) they're just adjusting their behaviour in preparation for another survival challenge.

If they've completely left the area, it's more likely related to food or cover rather than pressure.

If they've suddenly become completely nocturnal, but still in your area it's probably a more general behaviour adjustment. Try finding their day beds and very cautiously setting up near there - throughout the day they do get up and move/shift within that area and give you a shot. Be careful whitetail are extremely finicky about their secure area - blow that and they will pack up and move.

If they're only active at night, but utterly avoiding areas you hunt, travel etc then they're probably onto you. The good news is they're not likely to move far unless you've blown their bedding/secure area.

thanks