I don’t think this was just an Infection on its own causing this, I have a feeling the coral went downhill then got infected.
This may have been due to lack of PAR as I see you run only whites (I’ve not found white to push much PAR so I always run Atleast 15% of blues depending on how strong the light is).
Torches in general are incredibly picky, I’m 4 years into my tank and only now keeping a torch that actually splits.
You may find an imbalance of bacteria is currently in your tank as that generally causes torches to wilt after even being incredibly happy. I had it happen with my 20+ head colony and now it’s staying in the 1 head group… this also caused my Joker Torch to wilt after only a week in the tank. And yes, I was running UV during these two issues and I still do. It does help with some things but other issues it doesn’t help with.