Yes, it's wild how frequently often Crits come from creatures that are only 1 level higher. And the crits are so much worse than they are in other recent editions.Look at the numbers of sever/extreme encounters. They are almost always decided by crit or no crit of the enemy. This level of fight is very swingy in the NPC favor. A single crit doesn't make a TPK happen, but it certainly will put the PCs on their heels. It can just continue to go downhill from there.