Overpopulation

[Minimalist]

Not exactly.  You forgot to account for infant mortality which is higher in some places than others.

https://en.wikipedia.org/wiki/Sub-replacement_fertility

Sub-replacement fertility is a total fertility rate (TFR) that (if sustained) leads to each new generation being less populous than the previous one in a given area. In developed countries sub-replacement fertility is any rate below approximately 2.1 children born per woman, but the threshold can be as high as 3.4 in some developing countries because of higher mortality rates.[1] Taken globally, the total fertility rate at replacement was 2.33 children per woman in 2003