Nutrient toxicity or deficiency?

Yup it's nitrogen tox. You can tell by the way your leafs are falling in on top of each other, (leaf degradation). The shiny green, hmm, you can also get that from silca it's more the blistering look that leaf deg. I show that cery thing and the fix. In tangetine dream, its just a simple case of removing what you can do without but dont take too much defol, as each leaf is like a "mini power station" im quoting another grower who used that, but basically leafs take in energy even the sickly ones. But leafs with deg are dead and of no use. Remove them. My leafs are shiny cause of rhino skin.

Yes, this certainly looks like nitrogen toxicity, you ca n by the dark shiny green fan leaves. Easy fix though she just needs a minor flush and only ph balanced water until she perks back up.