My Lvl 14 smite dealt 567 damage to drake, wtf

It was the last drake we needed for mountain soul, both me and the enemy jungler are lvl 14 with smites that should deal 800 true damage, my team and me are on drake and it seems like a won drake for us, enemy jungler jumps in trying to steal, he smites it at 1543 damge, it's health drops to 692, i smite it with my LVL 14 SMITE, which is supposed to do 800 true damage, but after the smite the drake still has 125 health, and in that instance the enemy jungler finishes it off with an ability, WTF why did my smite deal 567 damage????