I do truly hope insect biomass decline is uncorrelated to global climate change, and has more to do with local land use (farming, concrete, fertilizer, etc). That would mean we could make significant progress on restoring land-based insect biodiversity even with smaller community initiatives.

My point was more that this is a thing which has apparently been going on for decades...and we just didn't notice. What else might we not be noticing?

A whole lot that probably doesn't matter.