Thanks, ER333, and others. I’m visiting family so I’m not as attentive to the discussion as I could be.
I wonder if they intend on filling under that left corner or not.
We can't see how deep it goes under that corner, but based on the shadows it might be a water channel eroded into soft/weathered rock.
It's easy to see how a lot of water could have been flowing under that slab. If they fill the hole in and trap the water I can see how it might even make matters worse. The water is going to get out somewhere.