I haven’t seen a response, but I’m not sure what you’d want to hear. This is by design – it isn’t a bug or anything. If the bulb loses power and then power is restored, it will turn on. This is so that it can be used with normal switches. You could vote for this wishlist item if you’re not a fan of that behavior.
If the bulbs are remaining offline after a power outage, that’s different than what this thread is talking about. That shouldn’t happen, but it does sometimes. I’ve had it happen once or twice, although it’s only happened with one bulb at a time. (I have 5 in total) I’ve never seen it happen with all my bulbs at the same time. If they’re all offline, it sounds more like a router/internet issue.