Yujiku, I found this possible explanation on the internet.

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Oedema - Oedema is a problem that can affect houseplants, including braided money trees. It is caused by excess moisture on the plant and a lack of light. Oedema can be identified by wilting and yellowing leaves or corklike spots that form on the foliage. Move the plant to an area where it receives more warmth and light, ensure the planter is draining and pinch off or prune affected leaves.