Nearly every photo showing the DPRK as having no lights at night is fake to some degree.

Now it is important to know that the North and Eastern parts of the DPRK are very mountainous so you are only going to see light on the Western/North West Coastal side mostly. That's because that's where all the people are.

But generally the pictures shown are from when there are blackouts, which still happen being a country under embargo, but it's not all the time. Secondly they are usually composites, so they've combined multiple blackouts to make it look like there's no lights. It like if you overlapped a whole lot of satellite photos post hurricanes and storms in the USA to suggest the USA was worse off in those regions.

Also photoshop and other exaggeration measures.