A declining population would not inherently be a problem. Low population growth is a concern only in that it is associated with a demographic problem, but the demographic problem is itself a problem only in that it raises concerns about how to support lots of elderly people, and there are many solutions there, only some of which involve higher population growth (for instance, increased taxation, increased automation, raised retirement ages, etc etc). And it is inherently a _temporary_ problem; eventually birth rates will stabilise at a new normal (this may already be happening in many places), the bulge in the population chart will age out, and normality will resume at a lower base.

This isn't even _that_ novel; major wars, for instance, tend to produce a temporary deficit of working age people vs elderly, as do certain disease epidemic (the 1918 flu pandemic preferentially killed young people, for instance).

Some people seem to extrapolate low population increase to _human extinction_ or something, but this really makes very little sense; lower birth rates doesn't mean _zero_ birth rates.

It doesn't count if it merely says "population is decreasing"; that's assuming the premise.

There is ONLY a problem if it contradicts a desirable goal - and by your post, that goal is apparently universal. Good luck with that.