Water chemistry is very high on the list of potential causes. Knowing exactly what they are is key. It helps us narrow down and possibly eliminate that as a cause of stress to the coral. Respectfully, not sharing that with us doesn't help us help you.
The want to help is genuine here, but most if not all of us are of us understand that water parameters and RO/DI source water, light intensity with proper spectrum and proper photoperiod schedule, age of the tank, flow, health of corals purchased before placement in our DT, overall husbandry, stability of your tank, bacterial strains, potential contamination from outside sources, pests and strict coral dipping practices......etc
All and more can contribute to coral stress. Without those water parameters to work with, well it's just a guessing game and doesn't help us help you.
Said in all do respect to you.