Yes, it sounds very much like the hub went off-line because of a power failure, not just an Internet outage. Then when power was restored, even if it was only out for a second or two, the smart bulbs came on full brightness. That is typical default behavior.
If you have Hue bulbs attached to a Hue bridge, you can set the power outage behavior for each individual bulb, but most other brands do not offer this feature.
As an alternative, some community members use a “canary bulb” and when it is restored to power, they have an automation that turns off all of the other lights they want turned off.
That’s more work than most people want to do, but it is useful for some households. Or if you’re going on vacation.
