I’ve had ich before on my clowns but they were white spots, this is almost like biggish white marks on the fins. I notice he gets chased around a lot so not sure if it’s damage or not. There currently in QT
Lymphocystis is pretty rare in green chromis (can show up though). I can't rule out ich, the photos just aren't clear enough, not uncommon for fish to have multiple issues at the same time. It does look like it is getting picked on. They are in QT - are you dosing copper? You may need to isolate this one to keep it from being attacked.