Spark plug stripped?

I am doing a tune up on a truck I recently bought. While changing out the plugs and coils I am having issues with the infamous back passenger side. For the life of me I could not get the wrench to grab on. Finally I got an endoscopic camera and this is what I found. It does not appear to be broken but the top is seated way lower than what the new one is that I just installed. (2nd photo) is this snapped? Based on how worn the top is I'm wondering if the previous owner never changed this one since it is hard to get to and it is still the original. I just don't understand how it is seated so much lower.