It depends on what you consider the issue to be. If anyone is both an environmentalist/conservationist and honest about it, a reduction in population would be a good outcome for biodiversity and would permit rewilding land currently used for agriculture, housing, commerce, etc. In the context of our current economic systems, a declining population is a disaster waiting to happen.
>China’s Population on Track to Peak Before 2025 as Births Drop
Almost exactly at the same time as Taiwan's population is expected to peak. South Korean and Japanese populations are already in decline.