The rest of em are good and same soil and water
New growth looks solid so wouldn’t worry too much just yet. Could be overwatering though, unless you just watered before that pic
All plants are different. This one seems to be picky. I think it is an issue with your pH. Always start with your pH. It can be the cause of most issues. I commented on your other post about your plant.
What substrate are u using?
My plants had the same issue, in my case on coco fiber + perlita and i was underwaterring with my solution
I think it was over watered new growth looks good now and using less water per watering hopefully that does the trick. It’s soil ff but not oven forest the lighter one
Not ocean forest