Overpopulation was widely popularized as a major threat to humanity in the 1960’s and 70’s…

We're on borrowed time. Once the US stops global blue water trade overwatch and the period of 'any nation can trade with any nation' (AKA 'the global order’) ends a lot of places that either cannot now produce enough food for their population - or that has poor enough soil that amendments are required (e.g. Brazil, Sub-Saharan Africa) things are going to be... not good. The US has been doing this at its own expense since the end of WWII but it's getting less interested in continuing.

Then there's energy. Fritz Haber's process of producing plant-usable nitrogen from atmospheric uses gobs and gobs of energy. With Russian gas going off-market, Europe has stopped producing them. More impact on the countries that need to amend soils already having issues over missing potash (which is mined, then shipped, but without overwatch...)

The Green Revolution (all the above plus plant genetics) has pushed Malthus off - but it's been getting more and more precarious. The current challenge is plants that can deal with soil salinity (we all know why) - but I don't see plants that don't need nitrogen or potassium on the horizon.

Agreed that economies (at least the ones we've lived in since forever) depend on growth and lack of growth has been an anomaly, but we're going to have to deal with it as it's already too late in much of the world. The Boomers pretty much everywhere other than the US gave having kids a hard pass. If you look at the demographics in, for example Europe or Russia of China, the demographics are upside-down (too few people of childbearing age). In China and the ethnic-Russian part of the RF, it's already too late.

This already happened to Japan in the 80s (remember when Japan was developing so fast it was going to eclipse the rest of the world?). We might look there for how to handle what's coming.

BTW, my wife and I chose not to have kids (back in the 80s) because things looked so dire - and someone in the US takes a lot more resources than someone pretty much anywhere else.