Please do not cut off the leaf. Removing a leaf before it is completely brown inhibits it's growth. Plants relocate mobile nutrients from older/dying leaves to newer ones. Be patient and let the plant do its thing.

Browning in the middle of the variegation is usually due to a drastic change in light. This causes what is essentially a sunburn.

A few tricks from way to many decades growing them. They like direct morning or evening sunlight for 3-4 hours. Watering - completely saturated the pot then allow it to dry out (I water mine only once a month or two). Fertilizer - they do best with a fertilizer with a 3:1:2 NPK ratio. You can give them a bit extra K when they are putting out a new leaf.

Do not move the plant if possible. Rotating them is a great way to mess them up and get sunburn.

Get a bidet

I don't know much to be useful in id-ing on sight, but can you describe the conditions it's been in? Is the soil well-draining? How long does it take for the top inch of soil to appear dried out, and how often are you watering? Did you repot it recently, and/or is the pot the right size (just a bit bigger than the roots)? How often are you using fertilizer? Is it getting any direct light? How many direct and indirect light hours total do you think? Is it autumn where you are and it's adjusting to less light, or vice versa?

Not thar knowledgeable myself, hopefully someone else can help!