It’s unlikely to be a good old fashioned carbonate (as in limestone) sinkhole. If it was a problem, it would be a problem for the whole area, and not just your house. If you’re really worried about it being a sinkhole, you should get a structural engineer out to look at it. Generally the remedy for real sinkholes is just to fill it in with as much cement or blcktop or whatever as possible (which doesn’t really last, because it’s a sinkhole, and it will keep happening). Also, fun fact: most homeowner’s insurance policies don’t cover sinkholes, but there are some that do.
It’s probably something that was buried and collapsed/caved in with the rain.