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Any idea on what deficiencie

Maybe just nothing if it’s the only spot. Try posting in the plant problem forum and add a pic of the whole plant.

It's probably calcium deficiency, which is common. This can be caused by not supplying enough calcium, or having the pH out of range to where the plant can't absorb and transport the calcium throughout the plant.

Leaves commonly get spots like this. They don't repair themselves, so don't expect the spots to go away. Just make sure it doesn't worsen, and keep an eye on your new growth, which is where you can look for ongoing issues.