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It looks dehydrated. When they are dehydrated the older leaves show it first and if it get's too bad it will drop the oldest leaves and will hang on to the newest as long as it can.
How are the roots, what is it potted in, how often do you water?
The first thing I would do is take a look at the roots, if they are hollow or mush then they are bad, if they are firm they are good.
Dehydration can be caused by both too MUCH water and too LITTLE water. Too much water suffocates the roots, they like plenty but they like air as well. By checking the roots if they are healthy then you might be under watering. If they or rotting then you might be over watering.
If they are rotting then you need to cut off the dead ones and repot.