Certified GKH Gardening Expert
this appears to be a lack of light. It is possible that it is a lack of nitrogen, as well. Fertilize once a year with a well rounded fertilizer, and try to put this in a south facing window.
Here is an article for more help with the palm: https://www.gardeningknowhow.com/houseplants/ponytail-palm/ponytail-palm-care.htm
Your Ponytail needs to be very close to a moderately sunny window. Improper watering can also be contributing to the problem. Allow the top surface of the soil to dry before adding just enough water until a bit runs through the drain holes. Do not let it sit in excess water.
Nitrogen is not a problem here.