Had this happen once. Went to do a slight adjustment with full weight on the suspension and the threads let go. That was a scary moment when the wrench went flying and the vehicle dropped. I had just put the entire suspension together and all looked ok when reassembling.

My guess is for this OP the one bar is going soft or maybe it was the wrong bar reinstalled? If lucky the partial part number could be visible from the cross brace opening, if it isn't flipped around.

It is not unusual for the adjusters to be different settings. There are few scenarios.
Torsion bars are spring steel, and for one to be precisely the same strength as the other is unlikely, and they could have fatigue too.
The rear springs also play into this. If you have a rear spring with a higher arch to it, that will force the opposite front corner down. You then would need to crank that front adjuster up, to compensate.
And, if the car has ever been put in the ditch, or crashed with one front rail kicked up, the car is no longer level to the datum plane. Meaning it has a twist. There are way more cars with that issue than you would think. A wide gap at the lower fender to rocker on one side is a quick indication of that. These old cars have lots of adjustment and slotted holes for a reason. The front fenders can be moved around a lot, to compensate for a twisted front structure. You can adjust the fenders around to hide a significant wist in the front structure.
If the front of the body is perfectly level to the level floor, and the rear of the body is not, your car is twisted. The adjuster is cranked way up trying to compensate.
Try this:
Ideally you would do this on a frame rack which provides a perfect level surface, but if you have a very good level concrete floor, that will suffice.
Put the car up on 4 jack stands at the ends of the rockers [torque boxes], and level it so the rockers measure identical side to side, to the level floor. This will place the center of the car perfectly level with the floor [datum plane]. It is very uncommon for the center section of a car to twist, so this section should be virtually perfect as far as measurement from the rocker to the floor.
Now, measure the ends of the frame rails to the floor. The rears are generally quite level, unless the car has had a significant rear end collision. a little varience is not unusual even from new.
Measure the front rails close the rad support, down to the floor. If one front rail is noticeably different measurement, then your front structure is twisted. It is most common for the right rail to measure higher from the floor, due to cars hitting the ditch. Frame rails will kick upward from an impact, causing a wide fender to rocker gap on that side, making the car sit low on that corner, so that torsion bar adjuster will need to be cranked in to raise that corner.
While measuring, also measure the 4 wheel openings to the floor. If the car is truly square, every measurement will be identical from side to side. If the rockers are square to the floor, and the wheel openings are not, then something is off. Usually it's one front rail kicked up.

Yes it was a little scary when it let go. I had ratchet and socket on a short piece of pipe so I didn't have to get so far under the car.