Need help with gigantea alba

[Narissa44]

Hello. I've had my gigantea alba for about a year now and it's seemed to be doing decent so far. But I've noticed the edges are yellow and there is a transparent spot. And I was hoping it is from nutrition deficiency and not an infection or rot. Does anyone have a clue on what this could be? Please and thank you. I just got done watering this plant so the moss is wet obviously. It's roots are green and healthy it's just the newest leaf that is concerning me. He's located in my bathroom on the sill of a frosted window. The window never really gets hot but the sun makes it a warm spot. We live in Florida and had a small cold spell for a few weeks. But all my other orchids in the same location are doing fine. And the white powder on the leaves are diatomaceous earth. I don't see any pests or anything.