Sounds like the CIDS system (Cabin Intercommunication Data System) was having a 'moment'. It controls all the cabin lighting, PA system, call bell lights, seat belt signs etc. and all the displays for the cabin crew. https://hursts.org.uk/airbus-technic...l/ar01s10.html

If you're on the ground, the system can be reset by the flight crew which knocks everything out and all the lights flash on and off for a while, before it comes back on. Airborne, the system wouldn't normally be reset as we lose the PA system, control of the lighting etc. So if it was an intermittent fault (as this seems to be, and bear in mind, I am a mere M&S sandwich seller and have no more technical knowledge than is provided in our manuals, and talking to engineers and flight crew), they would probably leave it until the next turnaround to reset it. There is no special call for flight crew digestive issues!

The 767 disco lights and call bell symphony is just a delight. I'm always amazed how few passengers even notice it's going on!