Hard to tell for sure with that pic but it could be nothing more than normal aging. When catts get big enough, the oldest growths do eventually die back. It's typically a slow process and the plants seem to absorb those older growths...the leaves, as well as the pbulbs, will gradually dry up and turn to sticks. Some will only lose the leaves and you're left with leafless pbulbs.
This can also happen after major root loss. Example - after a rough dividing of a large plant. In this case, the orchid truly does "eat" the older growths in order to provide energy to make new ones.
Next time...a pic of the whole plant before you remove anything would be better for diagnosing whatever is going on. It's too hard to know for sure with one partially shriveled growth.
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