Looking at https://www.macrotrends.net/cities/22812/cairo/population, that’s a slight slowdown from the 30 years it took them to go from 5 to 10 million or from 10 to 20 million, and looking at https://www.macrotrends.net/countries/EGY/egypt/population-g..., it may slow down further, but they need to build a lot of houses fast to accommodate that.
I, probably naively, took this as more of an efficiency move rather than political.
This certainly made it much more expensive as it was the middle of nowhere and there wasn't any infrastructure there.
https://www.frontiersin.org/articles/10.3389/feart.2020.0000...
They keep growing the city larger and larger. Leave for 20 years and come back, and you don't recognize the scenery anymore.
Actually that's true in the old city as well - there is a huge commercial sector and it's very dynamic and alive.