Surprising to me they look just like nuts and bolts I might tighten or loosen with my 1/2 inch drive socket set.
I can not tell which one is broken.
I’d just guess that the one closest to the camera is the bad one — look at how the nut isn’t quite screwed down all the way compared to the nuts on the other “still-tensioned” rods.
Look closely at the bolt in the center of the picture frame, look down to where it sits on the washer. Notice that it doesn'y look like any of the other nut/washer pairs visible. A portion of the nut facing the washer is visible and appears to be conical and extends a bit above the washer. That is only possible if there is no tension in the rod, which means the nut was not torqued down, or the rod has broken in two.
the broken one is the one in the foreground, where the nut is not seated closely to the socket, all the others are seated in the sockets.
Note the gap on the center one. It should be snug against the plate.