If you want a more precise diagnosis then please post a whole plant shot.
Usually when lower growth has been shed by the plant the leaves will become yellow/brown shrivel up and fall off. When they fall off the leaf stem is generally very pale.
Your leaf stems still look green and not at all like they fell off naturally.
You have multi coloured leaves with dying areas.
IMO these leaves have not come from lack of light.
There seems to be something else going on here IMO as you would expect the entire leaf to be yellow/brown.
J