Red Green War Coral Receding

My red/green war coral that I've had for 6 years has suddenly started receding over the past week--about 1/2 inch per day.  It seems to be triggered by a change in my LEDs but I started the new lights with less intensity than the old thinking the corals would need to adjust. It looks to me like the coral is dying off and not just bleached. Pic is included. Any thoughts would be appreciated!View attachment 1884
Are the lights the same brand & model? You may want to reduce the intensity a bit more if it won't affect other corals.You may also want to keep an eye on the candy cane, it may be their tentacles causing this.
Thanks for the feedback. No, the lights are different brands so I lowered the intensity of the new lights even more to see if it makes a difference.  The candy cane and war corals have co-existed where they are for the past several years so I don't think that's it but I will definitely keep an eye on it.