Why are my Philips Hue lights flickering on & off; by them selves?

So I have a heap of Philips Hue bulbs, with A Phoscon Conbee II running on a Raspberry Pi4 (I would give more details but they aren’t necessary).

One evening I’m on the back-patio with my laptop, playing around with HAss, when the kitchen lights start flickering on & off. I figure it must be a bug in one or more of my automation scripts, so I turn off all my automations; but it keeps happening. I check that no scripts are running & the logs for events being fired, but I can’t find the cause. It ends up stopping, & so I forget about it until a week later; it starts happening again!!! This time it’s at a really inconvenient time, so I just shut down HAss but it keeps happening for half an hour or so then stops. I figure it must be delayed actions or effects still being run on the lights them selves, until the next morning I get up to realise that I left the lights in the kitchen on all night. And would you guess what happened next, yep the lights start flickering again. But HAss is turned off still from the night before & it can’t be delayed effects this time, as the lights where fine for most of the evening after HAss was turned off & they did their thing, so what is going on?

So now i’m on a mission to reconnect all my bulbs back to my Philips Hue bridge (about 50 of them) so that i can update their firmware, & then reset the security keys on my Zigbee network.

What a pain, this is going to take about a week to do I recon. If anyone has an explanation to what is happening here, I would love to hear it?