so you can see enemy building foundations in the fog of war as long as you have scouted the area before, the grass changes to a preset shape depending on the building (I:E little stone square means castle, large tan block means TC) and can guess what the opponent is building there without the need to scout.
On a related note you can see deer and the like die in the fog of war as well giving information on villager locations.
I’m guessing this is just an oversight as both AOE 2 and 3 had similar fog of scouting issues. Seeing the wildlife die in the fog of war is directly from 3 so yeah.