Normal leaf base death?

[Plantking165]

I thought coconut leaf bases died slowly and turned light brown like this one its still dying slow and then my fiji is rapidly killing a leaf base in a span of 5 days it went from green and yellow to this dark color and dying is that a normal color and speed for the death of an old leaf base? If not what could be causing this?

[GottmitAlex]

Correct.