I can't see your locale, but again...it's that time of year. The caudex looks great, so I'm going to give it an initial call of "dormancy." Mine are doing the same, even under grow lights, with one or two exceptions out of 10.

The other solution might be leaf burn from the lights if they're too close and hot, but it doesn't look like that. The leaf clearly curves away slightly, and the burns aren't in consistent areas where the lights would approach.

You can keep it under light until it goes into dormancy if you really want, or pull the lighting back and let it go until February or so. Then warm it up, put it under light again, and let it burst back there until it's time to go outside.

While dormant, water once or (at maximum) twice a month, and keep an eye on it. A severely wilting caudex means water again--but underwatering is better than overwatering, which will lead to rotting.

Withhold feeding, or feed very, very lightly if you absolutely feel you must. :-) They won't be heavy feeders at all during winter.

Keep on southeastern, southern, or southwestern windowsills, which will be sufficient lighting during dormancy. Even if all the leaves drop (they sometimes don't, and dormant plants can even retain green leaves), the caudex will photosynthesize at a low level and will see the increasing sunlight as spring approaches. Try to avoid drafts under 45 degrees.

If that's not possible, use artificial lighting.