Because birth rates are dropping in every single country as people get educated and etc. 2nd generation immigrants are not having as many children either after

Because birth rates are dropping in every single country as people get educated and etc. 2nd generation immigrants are not having as many children either after the migrate so it is simply a stopgap until every country has a birthrate less than 2.1 (or whatever is needed to have stable population). That’s why I got curious what is this magical way of fixing the population decline.