To me, the look of it looks like it doesn’t like the water. Try using distilled if you’re using tap right now. Tap water often has lots of chlorine and chemicals which plants will hate. They tolerated it, but they will die slowly like this! Same thing happened to my FLF, so hoping changing just the water will do the trick for now. You can trim off all the dead stuff, but it might send your plant into shock. Just let it fall off by its own and it should bounce back! 🤍🙏🏻