I agree with all the other input. I’ve had a healthy bubble for a 3 years. Stability is the most important element. No big water changes, keep salinity the same. Best to leave it alone and let it recover.
So a few months down the line the bubble is getting some of her colour back, but i migrated to a bigger tank a few weeks ago, and she was getting some more flow then she used to.
She hates flow, i have another bubble coral that i have in literally still water with only slight water movement and she loves it, fully extended full colour no problems.
I have moved her to a new position (back of picture), you can see the front one is new and fully extended.
Will see how she gets on at the back.
I have noticed the coral is shedding some slime now and then is this normal? I know for some corals this is normal way of the coral getting rid of unwanted algae (if that's the right word).