You said it started blinking after power was restored. That’s how you know.
As for the app, you won’t be able to tell the difference between “unpaired” or “no power” or “no internet” in that scenario. It’s not possible for the app to know that.
I think your average “non-power user” is gonna figure it out once their lights stop working. Might have to hit the support pages, but if they set it up once, they can do it again.